<!DOCTYPE html> <html> <head> <title>underscore.js</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <meta name="viewport" content="width=device-width, target-densitydpi=160dpi, initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"> <link rel="stylesheet" media="all" href="docco.css" /> </head> <body> <div id="container"> <div id="background"></div> <ul class="sections"> <li id="title"> <div class="annotation"> <h1>underscore.js</h1> </div> </li> <li id="section-1"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-1">¶</a> </div> <pre><code>Underscore.js <span class="hljs-number">1.8</span><span class="hljs-number">.3</span> http:<span class="hljs-comment">//underscorejs.org</span> (c) <span class="hljs-number">2009</span>-<span class="hljs-number">2017</span> Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors Underscore may be freely distributed under the MIT license. </code></pre> </div> <div class="content"><div class='highlight'><pre> (<span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{</pre></div></div> </li> <li id="section-2"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-2">¶</a> </div> <h2 id="baseline-setup">Baseline setup</h2> </div> </li> <li id="section-3"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-3">¶</a> </div> </div> </li> <li id="section-4"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-4">¶</a> </div> <p>Establish the root object, <code>window</code> in the browser, or <code>exports</code> on the server.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> root = <span class="hljs-keyword">this</span>;</pre></div></div> </li> <li id="section-5"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-5">¶</a> </div> <p>Save the previous value of the <code>_</code> variable.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> previousUnderscore = root._;</pre></div></div> </li> <li id="section-6"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-6">¶</a> </div> <p>Save bytes in the minified (but not gzipped) version:</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> ArrayProto = <span class="hljs-built_in">Array</span>.prototype, ObjProto = <span class="hljs-built_in">Object</span>.prototype, FuncProto = <span class="hljs-built_in">Function</span>.prototype;</pre></div></div> </li> <li id="section-7"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-7">¶</a> </div> <p>Create quick reference variables for speed access to core prototypes.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> push = ArrayProto.push, slice = ArrayProto.slice, toString = ObjProto.toString, hasOwnProperty = ObjProto.hasOwnProperty;</pre></div></div> </li> <li id="section-8"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-8">¶</a> </div> <p>All <strong>ECMAScript 5</strong> native function implementations that we hope to use are declared here.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> nativeIsArray = <span class="hljs-built_in">Array</span>.isArray, nativeKeys = <span class="hljs-built_in">Object</span>.keys, nativeBind = FuncProto.bind, nativeCreate = <span class="hljs-built_in">Object</span>.create;</pre></div></div> </li> <li id="section-9"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-9">¶</a> </div> <p>Naked function reference for surrogate-prototype-swapping.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> Ctor = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span></span>{};</pre></div></div> </li> <li id="section-10"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-10">¶</a> </div> <p>Create a safe reference to the Underscore object for use below.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> _ = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">if</span> (obj <span class="hljs-keyword">instanceof</span> _) <span class="hljs-keyword">return</span> obj; <span class="hljs-keyword">if</span> (!(<span class="hljs-keyword">this</span> <span class="hljs-keyword">instanceof</span> _)) <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> _(obj); <span class="hljs-keyword">this</span>._wrapped = obj; };</pre></div></div> </li> <li id="section-11"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-11">¶</a> </div> <p>Export the Underscore object for <strong>Node.js</strong>, with backwards-compatibility for the old <code>require()</code> API. If we’re in the browser, add <code>_</code> as a global object.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> exports !== <span class="hljs-string">'undefined'</span>) { <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> <span class="hljs-built_in">module</span> !== <span class="hljs-string">'undefined'</span> && <span class="hljs-built_in">module</span>.exports) { exports = <span class="hljs-built_in">module</span>.exports = _; } exports._ = _; } <span class="hljs-keyword">else</span> { root._ = _; }</pre></div></div> </li> <li id="section-12"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-12">¶</a> </div> <p>Current version.</p> </div> <div class="content"><div class='highlight'><pre> _.VERSION = <span class="hljs-string">'1.8.3'</span>;</pre></div></div> </li> <li id="section-13"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-13">¶</a> </div> <p>Internal function that returns an efficient (for current engines) version of the passed-in callback, to be repeatedly applied in other Underscore functions.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> optimizeCb = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(func, context, argCount)</span> </span>{ <span class="hljs-keyword">if</span> (context === <span class="hljs-keyword">void</span> <span class="hljs-number">0</span>) <span class="hljs-keyword">return</span> func; <span class="hljs-keyword">switch</span> (argCount == <span class="hljs-literal">null</span> ? <span class="hljs-number">3</span> : argCount) { <span class="hljs-keyword">case</span> <span class="hljs-number">1</span>: <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value)</span> </span>{ <span class="hljs-keyword">return</span> func.call(context, value); }; <span class="hljs-keyword">case</span> <span class="hljs-number">2</span>: <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, other)</span> </span>{ <span class="hljs-keyword">return</span> func.call(context, value, other); }; <span class="hljs-keyword">case</span> <span class="hljs-number">3</span>: <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, index, collection)</span> </span>{ <span class="hljs-keyword">return</span> func.call(context, value, index, collection); }; <span class="hljs-keyword">case</span> <span class="hljs-number">4</span>: <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(accumulator, value, index, collection)</span> </span>{ <span class="hljs-keyword">return</span> func.call(context, accumulator, value, index, collection); }; } <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> func.apply(context, <span class="hljs-built_in">arguments</span>); }; };</pre></div></div> </li> <li id="section-14"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-14">¶</a> </div> <p>A mostly-internal function to generate callbacks that can be applied to each element in a collection, returning the desired result — either identity, an arbitrary callback, a property matcher, or a property accessor.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> cb = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, context, argCount)</span> </span>{ <span class="hljs-keyword">if</span> (value == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> _.identity; <span class="hljs-keyword">if</span> (_.isFunction(value)) <span class="hljs-keyword">return</span> optimizeCb(value, context, argCount); <span class="hljs-keyword">if</span> (_.isObject(value)) <span class="hljs-keyword">return</span> _.matcher(value); <span class="hljs-keyword">return</span> _.property(value); }; _.iteratee = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, context)</span> </span>{ <span class="hljs-keyword">return</span> cb(value, context, <span class="hljs-literal">Infinity</span>); };</pre></div></div> </li> <li id="section-15"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-15">¶</a> </div> <p>An internal function for creating assigner functions.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> createAssigner = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(keysFunc, undefinedOnly)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> length = <span class="hljs-built_in">arguments</span>.length; <span class="hljs-keyword">if</span> (length < <span class="hljs-number">2</span> || obj == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> obj; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> index = <span class="hljs-number">1</span>; index < length; index++) { <span class="hljs-keyword">var</span> source = <span class="hljs-built_in">arguments</span>[index], keys = keysFunc(source), l = keys.length; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>; i < l; i++) { <span class="hljs-keyword">var</span> key = keys[i]; <span class="hljs-keyword">if</span> (!undefinedOnly || obj[key] === <span class="hljs-keyword">void</span> <span class="hljs-number">0</span>) obj[key] = source[key]; } } <span class="hljs-keyword">return</span> obj; }; };</pre></div></div> </li> <li id="section-16"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-16">¶</a> </div> <p>An internal function for creating a new object that inherits from another.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> baseCreate = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(prototype)</span> </span>{ <span class="hljs-keyword">if</span> (!_.isObject(prototype)) <span class="hljs-keyword">return</span> {}; <span class="hljs-keyword">if</span> (nativeCreate) <span class="hljs-keyword">return</span> nativeCreate(prototype); Ctor.prototype = prototype; <span class="hljs-keyword">var</span> result = <span class="hljs-keyword">new</span> Ctor; Ctor.prototype = <span class="hljs-literal">null</span>; <span class="hljs-keyword">return</span> result; }; <span class="hljs-keyword">var</span> property = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(key)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> obj == <span class="hljs-literal">null</span> ? <span class="hljs-keyword">void</span> <span class="hljs-number">0</span> : obj[key]; }; };</pre></div></div> </li> <li id="section-17"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-17">¶</a> </div> <p>Helper for collection methods to determine whether a collection should be iterated as an array or as an object Related: <a href="http://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength">http://people.mozilla.org/~jorendorff/es6-draft.html#sec-tolength</a> Avoids a very nasty iOS 8 JIT bug on ARM-64. #2094</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> MAX_ARRAY_INDEX = <span class="hljs-built_in">Math</span>.pow(<span class="hljs-number">2</span>, <span class="hljs-number">53</span>) - <span class="hljs-number">1</span>; <span class="hljs-keyword">var</span> getLength = property(<span class="hljs-string">'length'</span>); <span class="hljs-keyword">var</span> isArrayLike = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(collection)</span> </span>{ <span class="hljs-keyword">var</span> length = getLength(collection); <span class="hljs-keyword">return</span> <span class="hljs-keyword">typeof</span> length == <span class="hljs-string">'number'</span> && length >= <span class="hljs-number">0</span> && length <= MAX_ARRAY_INDEX; };</pre></div></div> </li> <li id="section-18"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-18">¶</a> </div> <h2 id="collection-functions">Collection Functions</h2> </div> </li> <li id="section-19"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-19">¶</a> </div> </div> </li> <li id="section-20"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-20">¶</a> </div> <p>The cornerstone, an <code>each</code> implementation, aka <code>forEach</code>. Handles raw objects in addition to array-likes. Treats all sparse array-likes as if they were dense.</p> </div> <div class="content"><div class='highlight'><pre> _.each = _.forEach = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, context)</span> </span>{ iteratee = optimizeCb(iteratee, context); <span class="hljs-keyword">var</span> i, length; <span class="hljs-keyword">if</span> (isArrayLike(obj)) { <span class="hljs-keyword">for</span> (i = <span class="hljs-number">0</span>, length = obj.length; i < length; i++) { iteratee(obj[i], i, obj); } } <span class="hljs-keyword">else</span> { <span class="hljs-keyword">var</span> keys = _.keys(obj); <span class="hljs-keyword">for</span> (i = <span class="hljs-number">0</span>, length = keys.length; i < length; i++) { iteratee(obj[keys[i]], keys[i], obj); } } <span class="hljs-keyword">return</span> obj; };</pre></div></div> </li> <li id="section-21"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-21">¶</a> </div> <p>Return the results of applying the iteratee to each element.</p> </div> <div class="content"><div class='highlight'><pre> _.map = _.collect = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, context)</span> </span>{ iteratee = cb(iteratee, context); <span class="hljs-keyword">var</span> keys = !isArrayLike(obj) && _.keys(obj), length = (keys || obj).length, results = <span class="hljs-built_in">Array</span>(length); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> index = <span class="hljs-number">0</span>; index < length; index++) { <span class="hljs-keyword">var</span> currentKey = keys ? keys[index] : index; results[index] = iteratee(obj[currentKey], currentKey, obj); } <span class="hljs-keyword">return</span> results; };</pre></div></div> </li> <li id="section-22"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-22">¶</a> </div> <p>Create a reducing function iterating left or right.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">createReduce</span><span class="hljs-params">(dir)</span> </span>{</pre></div></div> </li> <li id="section-23"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-23">¶</a> </div> <p>Optimized iterator function as using arguments.length in the main function will deoptimize the, see #1991.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">iterator</span><span class="hljs-params">(obj, iteratee, memo, keys, index, length)</span> </span>{ <span class="hljs-keyword">for</span> (; index >= <span class="hljs-number">0</span> && index < length; index += dir) { <span class="hljs-keyword">var</span> currentKey = keys ? keys[index] : index; memo = iteratee(memo, obj[currentKey], currentKey, obj); } <span class="hljs-keyword">return</span> memo; } <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, memo, context)</span> </span>{ iteratee = optimizeCb(iteratee, context, <span class="hljs-number">4</span>); <span class="hljs-keyword">var</span> keys = !isArrayLike(obj) && _.keys(obj), length = (keys || obj).length, index = dir > <span class="hljs-number">0</span> ? <span class="hljs-number">0</span> : length - <span class="hljs-number">1</span>;</pre></div></div> </li> <li id="section-24"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-24">¶</a> </div> <p>Determine the initial value if none is provided.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (<span class="hljs-built_in">arguments</span>.length < <span class="hljs-number">3</span>) { memo = obj[keys ? keys[index] : index]; index += dir; } <span class="hljs-keyword">return</span> iterator(obj, iteratee, memo, keys, index, length); }; }</pre></div></div> </li> <li id="section-25"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-25">¶</a> </div> <p><strong>Reduce</strong> builds up a single result from a list of values, aka <code>inject</code>, or <code>foldl</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.reduce = _.foldl = _.inject = createReduce(<span class="hljs-number">1</span>);</pre></div></div> </li> <li id="section-26"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-26">¶</a> </div> <p>The right-associative version of reduce, also known as <code>foldr</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.reduceRight = _.foldr = createReduce(-<span class="hljs-number">1</span>);</pre></div></div> </li> <li id="section-27"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-27">¶</a> </div> <p>Return the first value which passes a truth test. Aliased as <code>detect</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.find = _.detect = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, predicate, context)</span> </span>{ <span class="hljs-keyword">var</span> key; <span class="hljs-keyword">if</span> (isArrayLike(obj)) { key = _.findIndex(obj, predicate, context); } <span class="hljs-keyword">else</span> { key = _.findKey(obj, predicate, context); } <span class="hljs-keyword">if</span> (key !== <span class="hljs-keyword">void</span> <span class="hljs-number">0</span> && key !== -<span class="hljs-number">1</span>) <span class="hljs-keyword">return</span> obj[key]; };</pre></div></div> </li> <li id="section-28"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-28">¶</a> </div> <p>Return all the elements that pass a truth test. Aliased as <code>select</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.filter = _.select = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, predicate, context)</span> </span>{ <span class="hljs-keyword">var</span> results = []; predicate = cb(predicate, context); _.each(obj, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, index, list)</span> </span>{ <span class="hljs-keyword">if</span> (predicate(value, index, list)) results.push(value); }); <span class="hljs-keyword">return</span> results; };</pre></div></div> </li> <li id="section-29"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-29">¶</a> </div> <p>Return all the elements for which a truth test fails.</p> </div> <div class="content"><div class='highlight'><pre> _.reject = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, predicate, context)</span> </span>{ <span class="hljs-keyword">return</span> _.filter(obj, _.negate(cb(predicate)), context); };</pre></div></div> </li> <li id="section-30"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-30">¶</a> </div> <p>Determine whether all of the elements match a truth test. Aliased as <code>all</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.every = _.all = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, predicate, context)</span> </span>{ predicate = cb(predicate, context); <span class="hljs-keyword">var</span> keys = !isArrayLike(obj) && _.keys(obj), length = (keys || obj).length; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> index = <span class="hljs-number">0</span>; index < length; index++) { <span class="hljs-keyword">var</span> currentKey = keys ? keys[index] : index; <span class="hljs-keyword">if</span> (!predicate(obj[currentKey], currentKey, obj)) <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; } <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>; };</pre></div></div> </li> <li id="section-31"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-31">¶</a> </div> <p>Determine if at least one element in the object matches a truth test. Aliased as <code>any</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.some = _.any = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, predicate, context)</span> </span>{ predicate = cb(predicate, context); <span class="hljs-keyword">var</span> keys = !isArrayLike(obj) && _.keys(obj), length = (keys || obj).length; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> index = <span class="hljs-number">0</span>; index < length; index++) { <span class="hljs-keyword">var</span> currentKey = keys ? keys[index] : index; <span class="hljs-keyword">if</span> (predicate(obj[currentKey], currentKey, obj)) <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>; } <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; };</pre></div></div> </li> <li id="section-32"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-32">¶</a> </div> <p>Determine if the array or object contains a given item (using <code>===</code>). Aliased as <code>includes</code> and <code>include</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.contains = _.includes = _.include = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, item, fromIndex, guard)</span> </span>{ <span class="hljs-keyword">if</span> (!isArrayLike(obj)) obj = _.values(obj); <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> fromIndex != <span class="hljs-string">'number'</span> || guard) fromIndex = <span class="hljs-number">0</span>; <span class="hljs-keyword">return</span> _.indexOf(obj, item, fromIndex) >= <span class="hljs-number">0</span>; };</pre></div></div> </li> <li id="section-33"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-33">¶</a> </div> <p>Invoke a method (with arguments) on every item in a collection.</p> </div> <div class="content"><div class='highlight'><pre> _.invoke = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, method)</span> </span>{ <span class="hljs-keyword">var</span> args = slice.call(<span class="hljs-built_in">arguments</span>, <span class="hljs-number">2</span>); <span class="hljs-keyword">var</span> isFunc = _.isFunction(method); <span class="hljs-keyword">return</span> _.map(obj, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value)</span> </span>{ <span class="hljs-keyword">var</span> func = isFunc ? method : value[method]; <span class="hljs-keyword">return</span> func == <span class="hljs-literal">null</span> ? func : func.apply(value, args); }); };</pre></div></div> </li> <li id="section-34"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-34">¶</a> </div> <p>Convenience version of a common use case of <code>map</code>: fetching a property.</p> </div> <div class="content"><div class='highlight'><pre> _.pluck = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, key)</span> </span>{ <span class="hljs-keyword">return</span> _.map(obj, _.property(key)); };</pre></div></div> </li> <li id="section-35"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-35">¶</a> </div> <p>Convenience version of a common use case of <code>filter</code>: selecting only objects containing specific <code>key:value</code> pairs.</p> </div> <div class="content"><div class='highlight'><pre> _.where = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, attrs)</span> </span>{ <span class="hljs-keyword">return</span> _.filter(obj, _.matcher(attrs)); };</pre></div></div> </li> <li id="section-36"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-36">¶</a> </div> <p>Convenience version of a common use case of <code>find</code>: getting the first object containing specific <code>key:value</code> pairs.</p> </div> <div class="content"><div class='highlight'><pre> _.findWhere = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, attrs)</span> </span>{ <span class="hljs-keyword">return</span> _.find(obj, _.matcher(attrs)); };</pre></div></div> </li> <li id="section-37"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-37">¶</a> </div> <p>Return the maximum element (or element-based computation).</p> </div> <div class="content"><div class='highlight'><pre> _.max = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, context)</span> </span>{ <span class="hljs-keyword">var</span> result = -<span class="hljs-literal">Infinity</span>, lastComputed = -<span class="hljs-literal">Infinity</span>, value, computed; <span class="hljs-keyword">if</span> (iteratee == <span class="hljs-literal">null</span> && obj != <span class="hljs-literal">null</span>) { obj = isArrayLike(obj) ? obj : _.values(obj); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = obj.length; i < length; i++) { value = obj[i]; <span class="hljs-keyword">if</span> (value > result) { result = value; } } } <span class="hljs-keyword">else</span> { iteratee = cb(iteratee, context); _.each(obj, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, index, list)</span> </span>{ computed = iteratee(value, index, list); <span class="hljs-keyword">if</span> (computed > lastComputed || computed === -<span class="hljs-literal">Infinity</span> && result === -<span class="hljs-literal">Infinity</span>) { result = value; lastComputed = computed; } }); } <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-38"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-38">¶</a> </div> <p>Return the minimum element (or element-based computation).</p> </div> <div class="content"><div class='highlight'><pre> _.min = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, context)</span> </span>{ <span class="hljs-keyword">var</span> result = <span class="hljs-literal">Infinity</span>, lastComputed = <span class="hljs-literal">Infinity</span>, value, computed; <span class="hljs-keyword">if</span> (iteratee == <span class="hljs-literal">null</span> && obj != <span class="hljs-literal">null</span>) { obj = isArrayLike(obj) ? obj : _.values(obj); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = obj.length; i < length; i++) { value = obj[i]; <span class="hljs-keyword">if</span> (value < result) { result = value; } } } <span class="hljs-keyword">else</span> { iteratee = cb(iteratee, context); _.each(obj, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, index, list)</span> </span>{ computed = iteratee(value, index, list); <span class="hljs-keyword">if</span> (computed < lastComputed || computed === <span class="hljs-literal">Infinity</span> && result === <span class="hljs-literal">Infinity</span>) { result = value; lastComputed = computed; } }); } <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-39"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-39">¶</a> </div> <p>Shuffle a collection, using the modern version of the <a href="http://en.wikipedia.org/wiki/Fisher–Yates_shuffle">Fisher-Yates shuffle</a>.</p> </div> <div class="content"><div class='highlight'><pre> _.shuffle = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> set = isArrayLike(obj) ? obj : _.values(obj); <span class="hljs-keyword">var</span> length = set.length; <span class="hljs-keyword">var</span> shuffled = <span class="hljs-built_in">Array</span>(length); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> index = <span class="hljs-number">0</span>, rand; index < length; index++) { rand = _.random(<span class="hljs-number">0</span>, index); <span class="hljs-keyword">if</span> (rand !== index) shuffled[index] = shuffled[rand]; shuffled[rand] = set[index]; } <span class="hljs-keyword">return</span> shuffled; };</pre></div></div> </li> <li id="section-40"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-40">¶</a> </div> <p>Sample <strong>n</strong> random values from a collection. If <strong>n</strong> is not specified, returns a single random element. The internal <code>guard</code> argument allows it to work with <code>map</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.sample = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, n, guard)</span> </span>{ <span class="hljs-keyword">if</span> (n == <span class="hljs-literal">null</span> || guard) { <span class="hljs-keyword">if</span> (!isArrayLike(obj)) obj = _.values(obj); <span class="hljs-keyword">return</span> obj[_.random(obj.length - <span class="hljs-number">1</span>)]; } <span class="hljs-keyword">return</span> _.shuffle(obj).slice(<span class="hljs-number">0</span>, <span class="hljs-built_in">Math</span>.max(<span class="hljs-number">0</span>, n)); };</pre></div></div> </li> <li id="section-41"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-41">¶</a> </div> <p>Sort the object’s values by a criterion produced by an iteratee.</p> </div> <div class="content"><div class='highlight'><pre> _.sortBy = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, context)</span> </span>{ iteratee = cb(iteratee, context); <span class="hljs-keyword">return</span> _.pluck(_.map(obj, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, index, list)</span> </span>{ <span class="hljs-keyword">return</span> { value: value, index: index, criteria: iteratee(value, index, list) }; }).sort(<span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(left, right)</span> </span>{ <span class="hljs-keyword">var</span> a = left.criteria; <span class="hljs-keyword">var</span> b = right.criteria; <span class="hljs-keyword">if</span> (a !== b) { <span class="hljs-keyword">if</span> (a > b || a === <span class="hljs-keyword">void</span> <span class="hljs-number">0</span>) <span class="hljs-keyword">return</span> <span class="hljs-number">1</span>; <span class="hljs-keyword">if</span> (a < b || b === <span class="hljs-keyword">void</span> <span class="hljs-number">0</span>) <span class="hljs-keyword">return</span> -<span class="hljs-number">1</span>; } <span class="hljs-keyword">return</span> left.index - right.index; }), <span class="hljs-string">'value'</span>); };</pre></div></div> </li> <li id="section-42"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-42">¶</a> </div> <p>An internal function used for aggregate “group by” operations.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> group = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(behavior)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, context)</span> </span>{ <span class="hljs-keyword">var</span> result = {}; iteratee = cb(iteratee, context); _.each(obj, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, index)</span> </span>{ <span class="hljs-keyword">var</span> key = iteratee(value, index, obj); behavior(result, value, key); }); <span class="hljs-keyword">return</span> result; }; };</pre></div></div> </li> <li id="section-43"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-43">¶</a> </div> <p>Groups the object’s values by a criterion. Pass either a string attribute to group by, or a function that returns the criterion.</p> </div> <div class="content"><div class='highlight'><pre> _.groupBy = group(<span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(result, value, key)</span> </span>{ <span class="hljs-keyword">if</span> (_.has(result, key)) result[key].push(value); <span class="hljs-keyword">else</span> result[key] = [value]; });</pre></div></div> </li> <li id="section-44"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-44">¶</a> </div> <p>Indexes the object’s values by a criterion, similar to <code>groupBy</code>, but for when you know that your index values will be unique.</p> </div> <div class="content"><div class='highlight'><pre> _.indexBy = group(<span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(result, value, key)</span> </span>{ result[key] = value; });</pre></div></div> </li> <li id="section-45"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-45">¶</a> </div> <p>Counts instances of an object that group by a certain criterion. Pass either a string attribute to count by, or a function that returns the criterion.</p> </div> <div class="content"><div class='highlight'><pre> _.countBy = group(<span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(result, value, key)</span> </span>{ <span class="hljs-keyword">if</span> (_.has(result, key)) result[key]++; <span class="hljs-keyword">else</span> result[key] = <span class="hljs-number">1</span>; });</pre></div></div> </li> <li id="section-46"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-46">¶</a> </div> <p>Safely create a real, live array from anything iterable.</p> </div> <div class="content"><div class='highlight'><pre> _.toArray = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">if</span> (!obj) <span class="hljs-keyword">return</span> []; <span class="hljs-keyword">if</span> (_.isArray(obj)) <span class="hljs-keyword">return</span> slice.call(obj); <span class="hljs-keyword">if</span> (isArrayLike(obj)) <span class="hljs-keyword">return</span> _.map(obj, _.identity); <span class="hljs-keyword">return</span> _.values(obj); };</pre></div></div> </li> <li id="section-47"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-47">¶</a> </div> <p>Return the number of elements in an object.</p> </div> <div class="content"><div class='highlight'><pre> _.size = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">if</span> (obj == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> <span class="hljs-number">0</span>; <span class="hljs-keyword">return</span> isArrayLike(obj) ? obj.length : _.keys(obj).length; };</pre></div></div> </li> <li id="section-48"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-48">¶</a> </div> <p>Split a collection into two arrays: one whose elements all satisfy the given predicate, and one whose elements all do not satisfy the predicate.</p> </div> <div class="content"><div class='highlight'><pre> _.partition = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, predicate, context)</span> </span>{ predicate = cb(predicate, context); <span class="hljs-keyword">var</span> pass = [], fail = []; _.each(obj, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, key, obj)</span> </span>{ (predicate(value, key, obj) ? pass : fail).push(value); }); <span class="hljs-keyword">return</span> [pass, fail]; };</pre></div></div> </li> <li id="section-49"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-55">¶</a> </div> <p>Trim out all falsy values from an object.</p> </div> <div class="content"><div class='highlight'><pre> _.compact = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> _.filter(obj, _.identity); };</pre></div></div> </li> <li id="section-50"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-49">¶</a> </div> <h2 id="array-functions">Array Functions</h2> </div> </li> <li id="section-51"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-50">¶</a> </div> </div> </li> <li id="section-52"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-51">¶</a> </div> <p>Get the first element of an array. Passing <strong>n</strong> will return the first N values in the array. Aliased as <code>head</code> and <code>take</code>. The <strong>guard</strong> check allows it to work with <code>_.map</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.first = _.head = _.take = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, n, guard)</span> </span>{ <span class="hljs-keyword">if</span> (array == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> <span class="hljs-keyword">void</span> <span class="hljs-number">0</span>; <span class="hljs-keyword">if</span> (n == <span class="hljs-literal">null</span> || guard) <span class="hljs-keyword">return</span> array[<span class="hljs-number">0</span>]; <span class="hljs-keyword">return</span> _.initial(array, array.length - n); };</pre></div></div> </li> <li id="section-53"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-52">¶</a> </div> <p>Returns everything but the last entry of the array. Especially useful on the arguments object. Passing <strong>n</strong> will return all the values in the array, excluding the last N.</p> </div> <div class="content"><div class='highlight'><pre> _.initial = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, n, guard)</span> </span>{ <span class="hljs-keyword">return</span> slice.call(array, <span class="hljs-number">0</span>, <span class="hljs-built_in">Math</span>.max(<span class="hljs-number">0</span>, array.length - (n == <span class="hljs-literal">null</span> || guard ? <span class="hljs-number">1</span> : n))); };</pre></div></div> </li> <li id="section-54"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-53">¶</a> </div> <p>Get the last element of an array. Passing <strong>n</strong> will return the last N values in the array.</p> </div> <div class="content"><div class='highlight'><pre> _.last = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, n, guard)</span> </span>{ <span class="hljs-keyword">if</span> (array == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> <span class="hljs-keyword">void</span> <span class="hljs-number">0</span>; <span class="hljs-keyword">if</span> (n == <span class="hljs-literal">null</span> || guard) <span class="hljs-keyword">return</span> array[array.length - <span class="hljs-number">1</span>]; <span class="hljs-keyword">return</span> _.rest(array, <span class="hljs-built_in">Math</span>.max(<span class="hljs-number">0</span>, array.length - n)); };</pre></div></div> </li> <li id="section-55"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-54">¶</a> </div> <p>Returns everything but the first entry of the array. Aliased as <code>tail</code> and <code>drop</code>. Especially useful on the arguments object. Passing an <strong>n</strong> will return the rest N values in the array.</p> </div> <div class="content"><div class='highlight'><pre> _.rest = _.tail = _.drop = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, n, guard)</span> </span>{ <span class="hljs-keyword">return</span> slice.call(array, n == <span class="hljs-literal">null</span> || guard ? <span class="hljs-number">1</span> : n); };</pre></div></div> </li> <li id="section-56"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-56">¶</a> </div> <p>Internal implementation of a recursive <code>flatten</code> function.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> flatten = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(input, shallow, strict, startIndex)</span> </span>{ <span class="hljs-keyword">var</span> output = [], idx = <span class="hljs-number">0</span>; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = startIndex || <span class="hljs-number">0</span>, length = getLength(input); i < length; i++) { <span class="hljs-keyword">var</span> value = input[i]; <span class="hljs-keyword">if</span> (isArrayLike(value) && (_.isArray(value) || _.isArguments(value))) {</pre></div></div> </li> <li id="section-57"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-57">¶</a> </div> <p>flatten current level of array or arguments object</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (!shallow) value = flatten(value, shallow, strict); <span class="hljs-keyword">var</span> j = <span class="hljs-number">0</span>, len = value.length; output.length += len; <span class="hljs-keyword">while</span> (j < len) { output[idx++] = value[j++]; } } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (!strict) { output[idx++] = value; } } <span class="hljs-keyword">return</span> output; };</pre></div></div> </li> <li id="section-58"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-58">¶</a> </div> <p>Flatten out an array, either recursively (by default), or just one level.</p> </div> <div class="content"><div class='highlight'><pre> _.flatten = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, shallow)</span> </span>{ <span class="hljs-keyword">return</span> flatten(array, shallow, <span class="hljs-literal">false</span>); };</pre></div></div> </li> <li id="section-59"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-59">¶</a> </div> <p>Return a version of the array that does not contain the specified value(s).</p> </div> <div class="content"><div class='highlight'><pre> _.without = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array)</span> </span>{ <span class="hljs-keyword">return</span> _.difference(array, slice.call(<span class="hljs-built_in">arguments</span>, <span class="hljs-number">1</span>)); };</pre></div></div> </li> <li id="section-60"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-60">¶</a> </div> <p>Produce a duplicate-free version of the array. If the array has already been sorted, you have the option of using a faster algorithm. Aliased as <code>unique</code>.</p> </div> <div class="content"><div class='highlight'><pre> _.uniq = _.unique = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, isSorted, iteratee, context)</span> </span>{ <span class="hljs-keyword">if</span> (!_.isBoolean(isSorted)) { context = iteratee; iteratee = isSorted; isSorted = <span class="hljs-literal">false</span>; } <span class="hljs-keyword">if</span> (iteratee != <span class="hljs-literal">null</span>) iteratee = cb(iteratee, context); <span class="hljs-keyword">var</span> result = []; <span class="hljs-keyword">var</span> seen = []; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = getLength(array); i < length; i++) { <span class="hljs-keyword">var</span> value = array[i], computed = iteratee ? iteratee(value, i, array) : value; <span class="hljs-keyword">if</span> (isSorted) { <span class="hljs-keyword">if</span> (!i || seen !== computed) result.push(value); seen = computed; } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (iteratee) { <span class="hljs-keyword">if</span> (!_.contains(seen, computed)) { seen.push(computed); result.push(value); } } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (!_.contains(result, value)) { result.push(value); } } <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-61"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-61">¶</a> </div> <p>Produce an array that contains the union: each distinct element from all of the passed-in arrays.</p> </div> <div class="content"><div class='highlight'><pre> _.union = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> _.uniq(flatten(<span class="hljs-built_in">arguments</span>, <span class="hljs-literal">true</span>, <span class="hljs-literal">true</span>)); };</pre></div></div> </li> <li id="section-62"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-62">¶</a> </div> <p>Produce an array that contains every item shared between all the passed-in arrays.</p> </div> <div class="content"><div class='highlight'><pre> _.intersection = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array)</span> </span>{ <span class="hljs-keyword">var</span> result = []; <span class="hljs-keyword">var</span> argsLength = <span class="hljs-built_in">arguments</span>.length; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = getLength(array); i < length; i++) { <span class="hljs-keyword">var</span> item = array[i]; <span class="hljs-keyword">if</span> (_.contains(result, item)) <span class="hljs-keyword">continue</span>; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> j = <span class="hljs-number">1</span>; j < argsLength; j++) { <span class="hljs-keyword">if</span> (!_.contains(<span class="hljs-built_in">arguments</span>[j], item)) <span class="hljs-keyword">break</span>; } <span class="hljs-keyword">if</span> (j === argsLength) result.push(item); } <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-63"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-63">¶</a> </div> <p>Take the difference between one array and a number of other arrays. Only the elements present in just the first array will remain.</p> </div> <div class="content"><div class='highlight'><pre> _.difference = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array)</span> </span>{ <span class="hljs-keyword">var</span> rest = flatten(<span class="hljs-built_in">arguments</span>, <span class="hljs-literal">true</span>, <span class="hljs-literal">true</span>, <span class="hljs-number">1</span>); <span class="hljs-keyword">return</span> _.filter(array, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value)</span></span>{ <span class="hljs-keyword">return</span> !_.contains(rest, value); }); };</pre></div></div> </li> <li id="section-64"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-64">¶</a> </div> <p>Zip together multiple lists into a single array — elements that share an index go together.</p> </div> <div class="content"><div class='highlight'><pre> _.zip = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> _.unzip(<span class="hljs-built_in">arguments</span>); };</pre></div></div> </li> <li id="section-65"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-65">¶</a> </div> <p>Complement of _.zip. Unzip accepts an array of arrays and groups each array’s elements on shared indices</p> </div> <div class="content"><div class='highlight'><pre> _.unzip = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array)</span> </span>{ <span class="hljs-keyword">var</span> length = array && _.max(array, getLength).length || <span class="hljs-number">0</span>; <span class="hljs-keyword">var</span> result = <span class="hljs-built_in">Array</span>(length); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> index = <span class="hljs-number">0</span>; index < length; index++) { result[index] = _.pluck(array, index); } <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-66"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-66">¶</a> </div> <p>Converts lists into objects. Pass either a single array of <code>[key, value]</code> pairs, or two parallel arrays of the same length — one of keys, and one of the corresponding values.</p> </div> <div class="content"><div class='highlight'><pre> _.object = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(list, values)</span> </span>{ <span class="hljs-keyword">var</span> result = {}; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = getLength(list); i < length; i++) { <span class="hljs-keyword">if</span> (values) { result[list[i]] = values[i]; } <span class="hljs-keyword">else</span> { result[list[i][<span class="hljs-number">0</span>]] = list[i][<span class="hljs-number">1</span>]; } } <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-67"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-67">¶</a> </div> <p>Generator function to create the findIndex and findLastIndex functions</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">createPredicateIndexFinder</span><span class="hljs-params">(dir)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, predicate, context)</span> </span>{ predicate = cb(predicate, context); <span class="hljs-keyword">var</span> length = getLength(array); <span class="hljs-keyword">var</span> index = dir > <span class="hljs-number">0</span> ? <span class="hljs-number">0</span> : length - <span class="hljs-number">1</span>; <span class="hljs-keyword">for</span> (; index >= <span class="hljs-number">0</span> && index < length; index += dir) { <span class="hljs-keyword">if</span> (predicate(array[index], index, array)) <span class="hljs-keyword">return</span> index; } <span class="hljs-keyword">return</span> -<span class="hljs-number">1</span>; }; }</pre></div></div> </li> <li id="section-68"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-68">¶</a> </div> <p>Returns the first index on an array-like that passes a predicate test</p> </div> <div class="content"><div class='highlight'><pre> _.findIndex = createPredicateIndexFinder(<span class="hljs-number">1</span>); _.findLastIndex = createPredicateIndexFinder(-<span class="hljs-number">1</span>);</pre></div></div> </li> <li id="section-69"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-69">¶</a> </div> <p>Use a comparator function to figure out the smallest index at which an object should be inserted so as to maintain order. Uses binary search.</p> </div> <div class="content"><div class='highlight'><pre> _.sortedIndex = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, obj, iteratee, context)</span> </span>{ iteratee = cb(iteratee, context, <span class="hljs-number">1</span>); <span class="hljs-keyword">var</span> value = iteratee(obj); <span class="hljs-keyword">var</span> low = <span class="hljs-number">0</span>, high = getLength(array); <span class="hljs-keyword">while</span> (low < high) { <span class="hljs-keyword">var</span> mid = <span class="hljs-built_in">Math</span>.floor((low + high) / <span class="hljs-number">2</span>); <span class="hljs-keyword">if</span> (iteratee(array[mid]) < value) low = mid + <span class="hljs-number">1</span>; <span class="hljs-keyword">else</span> high = mid; } <span class="hljs-keyword">return</span> low; };</pre></div></div> </li> <li id="section-70"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-70">¶</a> </div> <p>Generator function to create the indexOf and lastIndexOf functions</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">createIndexFinder</span><span class="hljs-params">(dir, predicateFind, sortedIndex)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(array, item, idx)</span> </span>{ <span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = getLength(array); <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> idx == <span class="hljs-string">'number'</span>) { <span class="hljs-keyword">if</span> (dir > <span class="hljs-number">0</span>) { i = idx >= <span class="hljs-number">0</span> ? idx : <span class="hljs-built_in">Math</span>.max(idx + length, i); } <span class="hljs-keyword">else</span> { length = idx >= <span class="hljs-number">0</span> ? <span class="hljs-built_in">Math</span>.min(idx + <span class="hljs-number">1</span>, length) : idx + length + <span class="hljs-number">1</span>; } } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (sortedIndex && idx && length) { idx = sortedIndex(array, item); <span class="hljs-keyword">return</span> array[idx] === item ? idx : -<span class="hljs-number">1</span>; } <span class="hljs-keyword">if</span> (item !== item) { idx = predicateFind(slice.call(array, i, length), _.isNaN); <span class="hljs-keyword">return</span> idx >= <span class="hljs-number">0</span> ? idx + i : -<span class="hljs-number">1</span>; } <span class="hljs-keyword">for</span> (idx = dir > <span class="hljs-number">0</span> ? i : length - <span class="hljs-number">1</span>; idx >= <span class="hljs-number">0</span> && idx < length; idx += dir) { <span class="hljs-keyword">if</span> (array[idx] === item) <span class="hljs-keyword">return</span> idx; } <span class="hljs-keyword">return</span> -<span class="hljs-number">1</span>; }; }</pre></div></div> </li> <li id="section-71"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-71">¶</a> </div> <p>Return the position of the first occurrence of an item in an array, or -1 if the item is not included in the array. If the array is large and already in sort order, pass <code>true</code> for <strong>isSorted</strong> to use binary search.</p> </div> <div class="content"><div class='highlight'><pre> _.indexOf = createIndexFinder(<span class="hljs-number">1</span>, _.findIndex, _.sortedIndex); _.lastIndexOf = createIndexFinder(-<span class="hljs-number">1</span>, _.findLastIndex);</pre></div></div> </li> <li id="section-72"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-72">¶</a> </div> <p>Generate an integer Array containing an arithmetic progression. A port of the native Python <code>range()</code> function. See <a href="http://docs.python.org/library/functions.html#range">the Python documentation</a>.</p> </div> <div class="content"><div class='highlight'><pre> _.range = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(start, stop, step)</span> </span>{ <span class="hljs-keyword">if</span> (stop == <span class="hljs-literal">null</span>) { stop = start || <span class="hljs-number">0</span>; start = <span class="hljs-number">0</span>; } step = step || <span class="hljs-number">1</span>; <span class="hljs-keyword">var</span> length = <span class="hljs-built_in">Math</span>.max(<span class="hljs-built_in">Math</span>.ceil((stop - start) / step), <span class="hljs-number">0</span>); <span class="hljs-keyword">var</span> range = <span class="hljs-built_in">Array</span>(length); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> idx = <span class="hljs-number">0</span>; idx < length; idx++, start += step) { range[idx] = start; } <span class="hljs-keyword">return</span> range; };</pre></div></div> </li> <li id="section-73"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-73">¶</a> </div> <h2 id="function-ahem-functions">Function (ahem) Functions</h2> </div> </li> <li id="section-74"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-74">¶</a> </div> </div> </li> <li id="section-75"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-75">¶</a> </div> <p>Determines whether to execute a function as a constructor or a normal function with the provided arguments</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> executeBound = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(sourceFunc, boundFunc, context, callingContext, args)</span> </span>{ <span class="hljs-keyword">if</span> (!(callingContext <span class="hljs-keyword">instanceof</span> boundFunc)) <span class="hljs-keyword">return</span> sourceFunc.apply(context, args); <span class="hljs-keyword">var</span> self = baseCreate(sourceFunc.prototype); <span class="hljs-keyword">var</span> result = sourceFunc.apply(self, args); <span class="hljs-keyword">if</span> (_.isObject(result)) <span class="hljs-keyword">return</span> result; <span class="hljs-keyword">return</span> self; };</pre></div></div> </li> <li id="section-76"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-76">¶</a> </div> <p>Create a function bound to a given object (assigning <code>this</code>, and arguments, optionally). Delegates to <strong>ECMAScript 5</strong>‘s native <code>Function.bind</code> if available.</p> </div> <div class="content"><div class='highlight'><pre> _.bind = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(func, context)</span> </span>{ <span class="hljs-keyword">if</span> (nativeBind && func.bind === nativeBind) <span class="hljs-keyword">return</span> nativeBind.apply(func, slice.call(<span class="hljs-built_in">arguments</span>, <span class="hljs-number">1</span>)); <span class="hljs-keyword">if</span> (!_.isFunction(func)) <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-built_in">TypeError</span>(<span class="hljs-string">'Bind must be called on a function'</span>); <span class="hljs-keyword">var</span> args = slice.call(<span class="hljs-built_in">arguments</span>, <span class="hljs-number">2</span>); <span class="hljs-keyword">var</span> bound = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> executeBound(func, bound, context, <span class="hljs-keyword">this</span>, args.concat(slice.call(<span class="hljs-built_in">arguments</span>))); }; <span class="hljs-keyword">return</span> bound; };</pre></div></div> </li> <li id="section-77"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-77">¶</a> </div> <p>Partially apply a function by creating a version that has had some of its arguments pre-filled, without changing its dynamic <code>this</code> context. _ acts as a placeholder, allowing any combination of arguments to be pre-filled.</p> </div> <div class="content"><div class='highlight'><pre> _.partial = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(func)</span> </span>{ <span class="hljs-keyword">var</span> boundArgs = slice.call(<span class="hljs-built_in">arguments</span>, <span class="hljs-number">1</span>); <span class="hljs-keyword">var</span> bound = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">var</span> position = <span class="hljs-number">0</span>, length = boundArgs.length; <span class="hljs-keyword">var</span> args = <span class="hljs-built_in">Array</span>(length); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>; i < length; i++) { args[i] = boundArgs[i] === _ ? <span class="hljs-built_in">arguments</span>[position++] : boundArgs[i]; } <span class="hljs-keyword">while</span> (position < <span class="hljs-built_in">arguments</span>.length) args.push(<span class="hljs-built_in">arguments</span>[position++]); <span class="hljs-keyword">return</span> executeBound(func, bound, <span class="hljs-keyword">this</span>, <span class="hljs-keyword">this</span>, args); }; <span class="hljs-keyword">return</span> bound; };</pre></div></div> </li> <li id="section-78"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-78">¶</a> </div> <p>Bind a number of an object’s methods to that object. Remaining arguments are the method names to be bound. Useful for ensuring that all callbacks defined on an object belong to it.</p> </div> <div class="content"><div class='highlight'><pre> _.bindAll = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> i, length = <span class="hljs-built_in">arguments</span>.length, key; <span class="hljs-keyword">if</span> (length <= <span class="hljs-number">1</span>) <span class="hljs-keyword">throw</span> <span class="hljs-keyword">new</span> <span class="hljs-built_in">Error</span>(<span class="hljs-string">'bindAll must be passed function names'</span>); <span class="hljs-keyword">for</span> (i = <span class="hljs-number">1</span>; i < length; i++) { key = <span class="hljs-built_in">arguments</span>[i]; obj[key] = _.bind(obj[key], obj); } <span class="hljs-keyword">return</span> obj; };</pre></div></div> </li> <li id="section-79"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-79">¶</a> </div> <p>Memoize an expensive function by storing its results.</p> </div> <div class="content"><div class='highlight'><pre> _.memoize = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(func, hasher)</span> </span>{ <span class="hljs-keyword">var</span> memoize = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(key)</span> </span>{ <span class="hljs-keyword">var</span> cache = memoize.cache; <span class="hljs-keyword">var</span> address = <span class="hljs-string">''</span> + (hasher ? hasher.apply(<span class="hljs-keyword">this</span>, <span class="hljs-built_in">arguments</span>) : key); <span class="hljs-keyword">if</span> (!_.has(cache, address)) cache[address] = func.apply(<span class="hljs-keyword">this</span>, <span class="hljs-built_in">arguments</span>); <span class="hljs-keyword">return</span> cache[address]; }; memoize.cache = {}; <span class="hljs-keyword">return</span> memoize; };</pre></div></div> </li> <li id="section-80"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-80">¶</a> </div> <p>Delays a function for the given number of milliseconds, and then calls it with the arguments supplied.</p> </div> <div class="content"><div class='highlight'><pre> _.delay = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(func, wait)</span> </span>{ <span class="hljs-keyword">var</span> args = slice.call(<span class="hljs-built_in">arguments</span>, <span class="hljs-number">2</span>); <span class="hljs-keyword">return</span> setTimeout(<span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span></span>{ <span class="hljs-keyword">return</span> func.apply(<span class="hljs-literal">null</span>, args); }, wait); };</pre></div></div> </li> <li id="section-81"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-81">¶</a> </div> <p>Defers a function, scheduling it to run after the current call stack has cleared.</p> </div> <div class="content"><div class='highlight'><pre> _.defer = _.partial(_.delay, _, <span class="hljs-number">1</span>);</pre></div></div> </li> <li id="section-82"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-82">¶</a> </div> <p>Returns a function, that, when invoked, will only be triggered at most once during a given window of time. Normally, the throttled function will run as much as it can, without ever going more than once per <code>wait</code> duration; but if you’d like to disable the execution on the leading edge, pass <code>{leading: false}</code>. To disable execution on the trailing edge, ditto.</p> </div> <div class="content"><div class='highlight'><pre> _.throttle = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(func, wait, options)</span> </span>{ <span class="hljs-keyword">var</span> context, args, result; <span class="hljs-keyword">var</span> timeout = <span class="hljs-literal">null</span>; <span class="hljs-keyword">var</span> previous = <span class="hljs-number">0</span>; <span class="hljs-keyword">if</span> (!options) options = {}; <span class="hljs-keyword">var</span> later = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ previous = options.leading === <span class="hljs-literal">false</span> ? <span class="hljs-number">0</span> : _.now(); timeout = <span class="hljs-literal">null</span>; result = func.apply(context, args); <span class="hljs-keyword">if</span> (!timeout) context = args = <span class="hljs-literal">null</span>; }; <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">var</span> now = _.now(); <span class="hljs-keyword">if</span> (!previous && options.leading === <span class="hljs-literal">false</span>) previous = now; <span class="hljs-keyword">var</span> remaining = wait - (now - previous); context = <span class="hljs-keyword">this</span>; args = <span class="hljs-built_in">arguments</span>; <span class="hljs-keyword">if</span> (remaining <= <span class="hljs-number">0</span> || remaining > wait) { <span class="hljs-keyword">if</span> (timeout) { clearTimeout(timeout); timeout = <span class="hljs-literal">null</span>; } previous = now; result = func.apply(context, args); <span class="hljs-keyword">if</span> (!timeout) context = args = <span class="hljs-literal">null</span>; } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (!timeout && options.trailing !== <span class="hljs-literal">false</span>) { timeout = setTimeout(later, remaining); } <span class="hljs-keyword">return</span> result; }; };</pre></div></div> </li> <li id="section-83"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-83">¶</a> </div> <p>Returns a function, that, as long as it continues to be invoked, will not be triggered. The function will be called after it stops being called for N milliseconds. If <code>immediate</code> is passed, trigger the function on the leading edge, instead of the trailing.</p> </div> <div class="content"><div class='highlight'><pre> _.debounce = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(func, wait, immediate)</span> </span>{ <span class="hljs-keyword">var</span> timeout, args, context, timestamp, result; <span class="hljs-keyword">var</span> later = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">var</span> last = _.now() - timestamp; <span class="hljs-keyword">if</span> (last < wait && last >= <span class="hljs-number">0</span>) { timeout = setTimeout(later, wait - last); } <span class="hljs-keyword">else</span> { timeout = <span class="hljs-literal">null</span>; <span class="hljs-keyword">if</span> (!immediate) { result = func.apply(context, args); <span class="hljs-keyword">if</span> (!timeout) context = args = <span class="hljs-literal">null</span>; } } }; <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ context = <span class="hljs-keyword">this</span>; args = <span class="hljs-built_in">arguments</span>; timestamp = _.now(); <span class="hljs-keyword">var</span> callNow = immediate && !timeout; <span class="hljs-keyword">if</span> (!timeout) timeout = setTimeout(later, wait); <span class="hljs-keyword">if</span> (callNow) { result = func.apply(context, args); context = args = <span class="hljs-literal">null</span>; } <span class="hljs-keyword">return</span> result; }; };</pre></div></div> </li> <li id="section-84"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-84">¶</a> </div> <p>Returns the first function passed as an argument to the second, allowing you to adjust arguments, run code before and after, and conditionally execute the original function.</p> </div> <div class="content"><div class='highlight'><pre> _.wrap = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(func, wrapper)</span> </span>{ <span class="hljs-keyword">return</span> _.partial(wrapper, func); };</pre></div></div> </li> <li id="section-85"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-85">¶</a> </div> <p>Returns a negated version of the passed-in predicate.</p> </div> <div class="content"><div class='highlight'><pre> _.negate = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(predicate)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> !predicate.apply(<span class="hljs-keyword">this</span>, <span class="hljs-built_in">arguments</span>); }; };</pre></div></div> </li> <li id="section-86"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-86">¶</a> </div> <p>Returns a function that is the composition of a list of functions, each consuming the return value of the function that follows.</p> </div> <div class="content"><div class='highlight'><pre> _.compose = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">var</span> args = <span class="hljs-built_in">arguments</span>; <span class="hljs-keyword">var</span> start = args.length - <span class="hljs-number">1</span>; <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">var</span> i = start; <span class="hljs-keyword">var</span> result = args[start].apply(<span class="hljs-keyword">this</span>, <span class="hljs-built_in">arguments</span>); <span class="hljs-keyword">while</span> (i--) result = args[i].call(<span class="hljs-keyword">this</span>, result); <span class="hljs-keyword">return</span> result; }; };</pre></div></div> </li> <li id="section-87"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-87">¶</a> </div> <p>Returns a function that will only be executed on and after the Nth call.</p> </div> <div class="content"><div class='highlight'><pre> _.after = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(times, func)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">if</span> (--times < <span class="hljs-number">1</span>) { <span class="hljs-keyword">return</span> func.apply(<span class="hljs-keyword">this</span>, <span class="hljs-built_in">arguments</span>); } }; };</pre></div></div> </li> <li id="section-88"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-88">¶</a> </div> <p>Returns a function that will only be executed up to (but not including) the Nth call.</p> </div> <div class="content"><div class='highlight'><pre> _.before = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(times, func)</span> </span>{ <span class="hljs-keyword">var</span> memo; <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">if</span> (--times > <span class="hljs-number">0</span>) { memo = func.apply(<span class="hljs-keyword">this</span>, <span class="hljs-built_in">arguments</span>); } <span class="hljs-keyword">if</span> (times <= <span class="hljs-number">1</span>) func = <span class="hljs-literal">null</span>; <span class="hljs-keyword">return</span> memo; }; };</pre></div></div> </li> <li id="section-89"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-89">¶</a> </div> <p>Returns a function that will be executed at most one time, no matter how often you call it. Useful for lazy initialization.</p> </div> <div class="content"><div class='highlight'><pre> _.once = _.partial(_.before, <span class="hljs-number">2</span>);</pre></div></div> </li> <li id="section-90"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-90">¶</a> </div> <h2 id="object-functions">Object Functions</h2> </div> </li> <li id="section-91"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-91">¶</a> </div> </div> </li> <li id="section-92"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-92">¶</a> </div> <p>Keys in IE < 9 that won’t be iterated by <code>for key in ...</code> and thus missed.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> hasEnumBug = !{toString: <span class="hljs-literal">null</span>}.propertyIsEnumerable(<span class="hljs-string">'toString'</span>); <span class="hljs-keyword">var</span> nonEnumerableProps = [<span class="hljs-string">'valueOf'</span>, <span class="hljs-string">'isPrototypeOf'</span>, <span class="hljs-string">'toString'</span>, <span class="hljs-string">'propertyIsEnumerable'</span>, <span class="hljs-string">'hasOwnProperty'</span>, <span class="hljs-string">'toLocaleString'</span>]; <span class="hljs-function"><span class="hljs-keyword">function</span> <span class="hljs-title">collectNonEnumProps</span><span class="hljs-params">(obj, keys)</span> </span>{ <span class="hljs-keyword">var</span> nonEnumIdx = nonEnumerableProps.length; <span class="hljs-keyword">var</span> constructor = obj.constructor; <span class="hljs-keyword">var</span> proto = (_.isFunction(constructor) && constructor.prototype) || ObjProto;</pre></div></div> </li> <li id="section-93"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-93">¶</a> </div> <p>Constructor is a special case.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> prop = <span class="hljs-string">'constructor'</span>; <span class="hljs-keyword">if</span> (_.has(obj, prop) && !_.contains(keys, prop)) keys.push(prop); <span class="hljs-keyword">while</span> (nonEnumIdx--) { prop = nonEnumerableProps[nonEnumIdx]; <span class="hljs-keyword">if</span> (prop <span class="hljs-keyword">in</span> obj && obj[prop] !== proto[prop] && !_.contains(keys, prop)) { keys.push(prop); } } }</pre></div></div> </li> <li id="section-94"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-94">¶</a> </div> <p>Retrieve the names of an object’s own properties. Delegates to <strong>ECMAScript 5</strong>‘s native <code>Object.keys</code></p> </div> <div class="content"><div class='highlight'><pre> _.keys = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">if</span> (!_.isObject(obj)) <span class="hljs-keyword">return</span> []; <span class="hljs-keyword">if</span> (nativeKeys) <span class="hljs-keyword">return</span> nativeKeys(obj); <span class="hljs-keyword">var</span> keys = []; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> key <span class="hljs-keyword">in</span> obj) <span class="hljs-keyword">if</span> (_.has(obj, key)) keys.push(key);</pre></div></div> </li> <li id="section-95"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-95">¶</a> </div> <p>Ahem, IE < 9.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (hasEnumBug) collectNonEnumProps(obj, keys); <span class="hljs-keyword">return</span> keys; };</pre></div></div> </li> <li id="section-96"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-96">¶</a> </div> <p>Retrieve all the property names of an object.</p> </div> <div class="content"><div class='highlight'><pre> _.allKeys = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">if</span> (!_.isObject(obj)) <span class="hljs-keyword">return</span> []; <span class="hljs-keyword">var</span> keys = []; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> key <span class="hljs-keyword">in</span> obj) keys.push(key);</pre></div></div> </li> <li id="section-97"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-97">¶</a> </div> <p>Ahem, IE < 9.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (hasEnumBug) collectNonEnumProps(obj, keys); <span class="hljs-keyword">return</span> keys; };</pre></div></div> </li> <li id="section-98"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-98">¶</a> </div> <p>Retrieve the values of an object’s properties.</p> </div> <div class="content"><div class='highlight'><pre> _.values = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> keys = _.keys(obj); <span class="hljs-keyword">var</span> length = keys.length; <span class="hljs-keyword">var</span> values = <span class="hljs-built_in">Array</span>(length); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>; i < length; i++) { values[i] = obj[keys[i]]; } <span class="hljs-keyword">return</span> values; };</pre></div></div> </li> <li id="section-99"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-99">¶</a> </div> <p>Returns the results of applying the iteratee to each element of the object In contrast to _.map it returns an object</p> </div> <div class="content"><div class='highlight'><pre> _.mapObject = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, context)</span> </span>{ iteratee = cb(iteratee, context); <span class="hljs-keyword">var</span> keys = _.keys(obj), length = keys.length, results = {}, currentKey; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> index = <span class="hljs-number">0</span>; index < length; index++) { currentKey = keys[index]; results[currentKey] = iteratee(obj[currentKey], currentKey, obj); } <span class="hljs-keyword">return</span> results; };</pre></div></div> </li> <li id="section-100"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-100">¶</a> </div> <p>Convert an object into a list of <code>[key, value]</code> pairs.</p> </div> <div class="content"><div class='highlight'><pre> _.pairs = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> keys = _.keys(obj); <span class="hljs-keyword">var</span> length = keys.length; <span class="hljs-keyword">var</span> pairs = <span class="hljs-built_in">Array</span>(length); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>; i < length; i++) { pairs[i] = [keys[i], obj[keys[i]]]; } <span class="hljs-keyword">return</span> pairs; };</pre></div></div> </li> <li id="section-101"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-101">¶</a> </div> <p>Invert the keys and values of an object. The values must be serializable.</p> </div> <div class="content"><div class='highlight'><pre> _.invert = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> result = {}; <span class="hljs-keyword">var</span> keys = _.keys(obj); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = keys.length; i < length; i++) { result[obj[keys[i]]] = keys[i]; } <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-102"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-102">¶</a> </div> <p>Return a sorted list of the function names available on the object. Aliased as <code>methods</code></p> </div> <div class="content"><div class='highlight'><pre> _.functions = _.methods = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> names = []; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> key <span class="hljs-keyword">in</span> obj) { <span class="hljs-keyword">if</span> (_.isFunction(obj[key])) names.push(key); } <span class="hljs-keyword">return</span> names.sort(); };</pre></div></div> </li> <li id="section-103"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-103">¶</a> </div> <p>Extend a given object with all the properties in passed-in object(s).</p> </div> <div class="content"><div class='highlight'><pre> _.extend = createAssigner(_.allKeys);</pre></div></div> </li> <li id="section-104"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-104">¶</a> </div> <p>Assigns a given object with all the own properties in the passed-in object(s) (<a href="https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object/assign">https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Object/assign</a>)</p> </div> <div class="content"><div class='highlight'><pre> _.extendOwn = _.assign = createAssigner(_.keys);</pre></div></div> </li> <li id="section-105"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-105">¶</a> </div> <p>Returns the first key on an object that passes a predicate test</p> </div> <div class="content"><div class='highlight'><pre> _.findKey = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, predicate, context)</span> </span>{ predicate = cb(predicate, context); <span class="hljs-keyword">var</span> keys = _.keys(obj), key; <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = keys.length; i < length; i++) { key = keys[i]; <span class="hljs-keyword">if</span> (predicate(obj[key], key, obj)) <span class="hljs-keyword">return</span> key; } };</pre></div></div> </li> <li id="section-106"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-106">¶</a> </div> <p>Return a copy of the object only containing the whitelisted properties.</p> </div> <div class="content"><div class='highlight'><pre> _.pick = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(object, oiteratee, context)</span> </span>{ <span class="hljs-keyword">var</span> result = {}, obj = object, iteratee, keys; <span class="hljs-keyword">if</span> (obj == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> result; <span class="hljs-keyword">if</span> (_.isFunction(oiteratee)) { keys = _.allKeys(obj); iteratee = optimizeCb(oiteratee, context); } <span class="hljs-keyword">else</span> { keys = flatten(<span class="hljs-built_in">arguments</span>, <span class="hljs-literal">false</span>, <span class="hljs-literal">false</span>, <span class="hljs-number">1</span>); iteratee = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, key, obj)</span> </span>{ <span class="hljs-keyword">return</span> key <span class="hljs-keyword">in</span> obj; }; obj = <span class="hljs-built_in">Object</span>(obj); } <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>, length = keys.length; i < length; i++) { <span class="hljs-keyword">var</span> key = keys[i]; <span class="hljs-keyword">var</span> value = obj[key]; <span class="hljs-keyword">if</span> (iteratee(value, key, obj)) result[key] = value; } <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-107"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-107">¶</a> </div> <p>Return a copy of the object without the blacklisted properties.</p> </div> <div class="content"><div class='highlight'><pre> _.omit = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, iteratee, context)</span> </span>{ <span class="hljs-keyword">if</span> (_.isFunction(iteratee)) { iteratee = _.negate(iteratee); } <span class="hljs-keyword">else</span> { <span class="hljs-keyword">var</span> keys = _.map(flatten(<span class="hljs-built_in">arguments</span>, <span class="hljs-literal">false</span>, <span class="hljs-literal">false</span>, <span class="hljs-number">1</span>), <span class="hljs-built_in">String</span>); iteratee = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value, key)</span> </span>{ <span class="hljs-keyword">return</span> !_.contains(keys, key); }; } <span class="hljs-keyword">return</span> _.pick(obj, iteratee, context); };</pre></div></div> </li> <li id="section-108"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-108">¶</a> </div> <p>Fill in a given object with default properties.</p> </div> <div class="content"><div class='highlight'><pre> _.defaults = createAssigner(_.allKeys, <span class="hljs-literal">true</span>);</pre></div></div> </li> <li id="section-109"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-109">¶</a> </div> <p>Creates an object that inherits from the given prototype object. If additional properties are provided then they will be added to the created object.</p> </div> <div class="content"><div class='highlight'><pre> _.create = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(prototype, props)</span> </span>{ <span class="hljs-keyword">var</span> result = baseCreate(prototype); <span class="hljs-keyword">if</span> (props) _.extendOwn(result, props); <span class="hljs-keyword">return</span> result; };</pre></div></div> </li> <li id="section-110"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-110">¶</a> </div> <p>Create a (shallow-cloned) duplicate of an object.</p> </div> <div class="content"><div class='highlight'><pre> _.clone = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">if</span> (!_.isObject(obj)) <span class="hljs-keyword">return</span> obj; <span class="hljs-keyword">return</span> _.isArray(obj) ? obj.slice() : _.extend({}, obj); };</pre></div></div> </li> <li id="section-111"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-111">¶</a> </div> <p>Invokes interceptor with the obj, and then returns obj. The primary purpose of this method is to “tap into” a method chain, in order to perform operations on intermediate results within the chain.</p> </div> <div class="content"><div class='highlight'><pre> _.tap = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, interceptor)</span> </span>{ interceptor(obj); <span class="hljs-keyword">return</span> obj; };</pre></div></div> </li> <li id="section-112"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-112">¶</a> </div> <p>Returns whether an object has a given set of <code>key:value</code> pairs.</p> </div> <div class="content"><div class='highlight'><pre> _.isMatch = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(object, attrs)</span> </span>{ <span class="hljs-keyword">var</span> keys = _.keys(attrs), length = keys.length; <span class="hljs-keyword">if</span> (object == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> !length; <span class="hljs-keyword">var</span> obj = <span class="hljs-built_in">Object</span>(object); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>; i < length; i++) { <span class="hljs-keyword">var</span> key = keys[i]; <span class="hljs-keyword">if</span> (attrs[key] !== obj[key] || !(key <span class="hljs-keyword">in</span> obj)) <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; } <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>; };</pre></div></div> </li> <li id="section-113"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-113">¶</a> </div> <p>Internal recursive comparison function for <code>isEqual</code>.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> eq = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(a, b, aStack, bStack)</span> </span>{</pre></div></div> </li> <li id="section-114"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-114">¶</a> </div> <p>Identical objects are equal. <code>0 === -0</code>, but they aren’t identical. See the <a href="http://wiki.ecmascript.org/doku.php?id=harmony:egal">Harmony <code>egal</code> proposal</a>.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (a === b) <span class="hljs-keyword">return</span> a !== <span class="hljs-number">0</span> || <span class="hljs-number">1</span> / a === <span class="hljs-number">1</span> / b;</pre></div></div> </li> <li id="section-115"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-115">¶</a> </div> <p>A strict comparison is necessary because <code>null == undefined</code>.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (a == <span class="hljs-literal">null</span> || b == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> a === b;</pre></div></div> </li> <li id="section-116"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-116">¶</a> </div> <p>Unwrap any wrapped objects.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (a <span class="hljs-keyword">instanceof</span> _) a = a._wrapped; <span class="hljs-keyword">if</span> (b <span class="hljs-keyword">instanceof</span> _) b = b._wrapped;</pre></div></div> </li> <li id="section-117"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-117">¶</a> </div> <p>Compare <code>[[Class]]</code> names.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> className = toString.call(a); <span class="hljs-keyword">if</span> (className !== toString.call(b)) <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; <span class="hljs-keyword">switch</span> (className) {</pre></div></div> </li> <li id="section-118"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-118">¶</a> </div> <p>Strings, numbers, regular expressions, dates, and booleans are compared by value.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">case</span> <span class="hljs-string">'[object RegExp]'</span>:</pre></div></div> </li> <li id="section-119"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-119">¶</a> </div> <p>RegExps are coerced to strings for comparison (Note: ‘’ + /a/i === ‘/a/i’)</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">case</span> <span class="hljs-string">'[object String]'</span>:</pre></div></div> </li> <li id="section-120"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-120">¶</a> </div> <p>Primitives and their corresponding object wrappers are equivalent; thus, <code>"5"</code> is equivalent to <code>new String("5")</code>.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">return</span> <span class="hljs-string">''</span> + a === <span class="hljs-string">''</span> + b; <span class="hljs-keyword">case</span> <span class="hljs-string">'[object Number]'</span>:</pre></div></div> </li> <li id="section-121"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-121">¶</a> </div> <p><code>NaN</code>s are equivalent, but non-reflexive. Object(NaN) is equivalent to NaN</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (+a !== +a) <span class="hljs-keyword">return</span> +b !== +b;</pre></div></div> </li> <li id="section-122"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-122">¶</a> </div> <p>An <code>egal</code> comparison is performed for other numeric values.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">return</span> +a === <span class="hljs-number">0</span> ? <span class="hljs-number">1</span> / +a === <span class="hljs-number">1</span> / b : +a === +b; <span class="hljs-keyword">case</span> <span class="hljs-string">'[object Date]'</span>: <span class="hljs-keyword">case</span> <span class="hljs-string">'[object Boolean]'</span>:</pre></div></div> </li> <li id="section-123"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-123">¶</a> </div> <p>Coerce dates and booleans to numeric primitive values. Dates are compared by their millisecond representations. Note that invalid dates with millisecond representations of <code>NaN</code> are not equivalent.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">return</span> +a === +b; } <span class="hljs-keyword">var</span> areArrays = className === <span class="hljs-string">'[object Array]'</span>; <span class="hljs-keyword">if</span> (!areArrays) { <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> a != <span class="hljs-string">'object'</span> || <span class="hljs-keyword">typeof</span> b != <span class="hljs-string">'object'</span>) <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>;</pre></div></div> </li> <li id="section-124"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-124">¶</a> </div> <p>Objects with different constructors are not equivalent, but <code>Object</code>s or <code>Array</code>s from different frames are.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> aCtor = a.constructor, bCtor = b.constructor; <span class="hljs-keyword">if</span> (aCtor !== bCtor && !(_.isFunction(aCtor) && aCtor <span class="hljs-keyword">instanceof</span> aCtor && _.isFunction(bCtor) && bCtor <span class="hljs-keyword">instanceof</span> bCtor) && (<span class="hljs-string">'constructor'</span> <span class="hljs-keyword">in</span> a && <span class="hljs-string">'constructor'</span> <span class="hljs-keyword">in</span> b)) { <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; } }</pre></div></div> </li> <li id="section-125"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-125">¶</a> </div> <p>Assume equality for cyclic structures. The algorithm for detecting cyclic structures is adapted from ES 5.1 section 15.12.3, abstract operation <code>JO</code>.</p> </div> </li> <li id="section-126"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-126">¶</a> </div> <p>Initializing stack of traversed objects. It’s done here since we only need them for objects and arrays comparison.</p> </div> <div class="content"><div class='highlight'><pre> aStack = aStack || []; bStack = bStack || []; <span class="hljs-keyword">var</span> length = aStack.length; <span class="hljs-keyword">while</span> (length--) {</pre></div></div> </li> <li id="section-127"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-127">¶</a> </div> <p>Linear search. Performance is inversely proportional to the number of unique nested structures.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (aStack[length] === a) <span class="hljs-keyword">return</span> bStack[length] === b; }</pre></div></div> </li> <li id="section-128"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-128">¶</a> </div> <p>Add the first object to the stack of traversed objects.</p> </div> <div class="content"><div class='highlight'><pre> aStack.push(a); bStack.push(b);</pre></div></div> </li> <li id="section-129"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-129">¶</a> </div> <p>Recursively compare objects and arrays.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (areArrays) {</pre></div></div> </li> <li id="section-130"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-130">¶</a> </div> <p>Compare array lengths to determine if a deep comparison is necessary.</p> </div> <div class="content"><div class='highlight'><pre> length = a.length; <span class="hljs-keyword">if</span> (length !== b.length) <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>;</pre></div></div> </li> <li id="section-131"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-131">¶</a> </div> <p>Deep compare the contents, ignoring non-numeric properties.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">while</span> (length--) { <span class="hljs-keyword">if</span> (!eq(a[length], b[length], aStack, bStack)) <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; } } <span class="hljs-keyword">else</span> {</pre></div></div> </li> <li id="section-132"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-132">¶</a> </div> <p>Deep compare objects.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> keys = _.keys(a), key; length = keys.length;</pre></div></div> </li> <li id="section-133"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-133">¶</a> </div> <p>Ensure that both objects contain the same number of properties before comparing deep equality.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (_.keys(b).length !== length) <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; <span class="hljs-keyword">while</span> (length--) {</pre></div></div> </li> <li id="section-134"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-134">¶</a> </div> <p>Deep compare each member</p> </div> <div class="content"><div class='highlight'><pre> key = keys[length]; <span class="hljs-keyword">if</span> (!(_.has(b, key) && eq(a[key], b[key], aStack, bStack))) <span class="hljs-keyword">return</span> <span class="hljs-literal">false</span>; } }</pre></div></div> </li> <li id="section-135"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-135">¶</a> </div> <p>Remove the first object from the stack of traversed objects.</p> </div> <div class="content"><div class='highlight'><pre> aStack.pop(); bStack.pop(); <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>; };</pre></div></div> </li> <li id="section-136"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-136">¶</a> </div> <p>Perform a deep comparison to check if two objects are equal.</p> </div> <div class="content"><div class='highlight'><pre> _.isEqual = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(a, b)</span> </span>{ <span class="hljs-keyword">return</span> eq(a, b); };</pre></div></div> </li> <li id="section-137"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-137">¶</a> </div> <p>Is a given array, string, or object empty? An “empty” object has no enumerable own-properties.</p> </div> <div class="content"><div class='highlight'><pre> _.isEmpty = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">if</span> (obj == <span class="hljs-literal">null</span>) <span class="hljs-keyword">return</span> <span class="hljs-literal">true</span>; <span class="hljs-keyword">if</span> (isArrayLike(obj) && (_.isArray(obj) || _.isString(obj) || _.isArguments(obj))) <span class="hljs-keyword">return</span> obj.length === <span class="hljs-number">0</span>; <span class="hljs-keyword">return</span> _.keys(obj).length === <span class="hljs-number">0</span>; };</pre></div></div> </li> <li id="section-138"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-138">¶</a> </div> <p>Is a given value a DOM element?</p> </div> <div class="content"><div class='highlight'><pre> _.isElement = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> !!(obj && obj.nodeType === <span class="hljs-number">1</span>); };</pre></div></div> </li> <li id="section-139"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-139">¶</a> </div> <p>Is a given value an array? Delegates to ECMA5’s native Array.isArray</p> </div> <div class="content"><div class='highlight'><pre> _.isArray = nativeIsArray || <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> toString.call(obj) === <span class="hljs-string">'[object Array]'</span>; };</pre></div></div> </li> <li id="section-140"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-140">¶</a> </div> <p>Is a given variable an object?</p> </div> <div class="content"><div class='highlight'><pre> _.isObject = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> type = <span class="hljs-keyword">typeof</span> obj; <span class="hljs-keyword">return</span> type === <span class="hljs-string">'function'</span> || type === <span class="hljs-string">'object'</span> && !!obj; };</pre></div></div> </li> <li id="section-141"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-141">¶</a> </div> <p>Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp, isError.</p> </div> <div class="content"><div class='highlight'><pre> _.each([<span class="hljs-string">'Arguments'</span>, <span class="hljs-string">'Function'</span>, <span class="hljs-string">'String'</span>, <span class="hljs-string">'Number'</span>, <span class="hljs-string">'Date'</span>, <span class="hljs-string">'RegExp'</span>, <span class="hljs-string">'Error'</span>], <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(name)</span> </span>{ _[<span class="hljs-string">'is'</span> + name] = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> toString.call(obj) === <span class="hljs-string">'[object '</span> + name + <span class="hljs-string">']'</span>; }; });</pre></div></div> </li> <li id="section-142"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-142">¶</a> </div> <p>Define a fallback version of the method in browsers (ahem, IE < 9), where there isn’t any inspectable “Arguments” type.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (!_.isArguments(<span class="hljs-built_in">arguments</span>)) { _.isArguments = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> _.has(obj, <span class="hljs-string">'callee'</span>); }; }</pre></div></div> </li> <li id="section-143"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-143">¶</a> </div> <p>Optimize <code>isFunction</code> if appropriate. Work around some typeof bugs in old v8, IE 11 (#1621), and in Safari 8 (#1929).</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> /./ != <span class="hljs-string">'function'</span> && <span class="hljs-keyword">typeof</span> <span class="hljs-built_in">Int8Array</span> != <span class="hljs-string">'object'</span>) { _.isFunction = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-keyword">typeof</span> obj == <span class="hljs-string">'function'</span> || <span class="hljs-literal">false</span>; }; }</pre></div></div> </li> <li id="section-144"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-144">¶</a> </div> <p>Is a given object a finite number?</p> </div> <div class="content"><div class='highlight'><pre> _.isFinite = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-built_in">isFinite</span>(obj) && !<span class="hljs-built_in">isNaN</span>(<span class="hljs-built_in">parseFloat</span>(obj)); };</pre></div></div> </li> <li id="section-145"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-145">¶</a> </div> <p>Is the given value <code>NaN</code>? (NaN is the only number which does not equal itself).</p> </div> <div class="content"><div class='highlight'><pre> _.isNaN = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> _.isNumber(obj) && obj !== +obj; };</pre></div></div> </li> <li id="section-146"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-146">¶</a> </div> <p>Is a given value a boolean?</p> </div> <div class="content"><div class='highlight'><pre> _.isBoolean = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> obj === <span class="hljs-literal">true</span> || obj === <span class="hljs-literal">false</span> || toString.call(obj) === <span class="hljs-string">'[object Boolean]'</span>; };</pre></div></div> </li> <li id="section-147"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-147">¶</a> </div> <p>Is a given value equal to null?</p> </div> <div class="content"><div class='highlight'><pre> _.isNull = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> obj === <span class="hljs-literal">null</span>; };</pre></div></div> </li> <li id="section-148"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-148">¶</a> </div> <p>Is a given variable undefined?</p> </div> <div class="content"><div class='highlight'><pre> _.isUndefined = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> obj === <span class="hljs-keyword">void</span> <span class="hljs-number">0</span>; };</pre></div></div> </li> <li id="section-149"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-149">¶</a> </div> <p>Shortcut function for checking if an object has a given property directly on itself (in other words, not on a prototype).</p> </div> <div class="content"><div class='highlight'><pre> _.has = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj, key)</span> </span>{ <span class="hljs-keyword">return</span> obj != <span class="hljs-literal">null</span> && hasOwnProperty.call(obj, key); };</pre></div></div> </li> <li id="section-150"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-150">¶</a> </div> <h2 id="utility-functions">Utility Functions</h2> </div> </li> <li id="section-151"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-151">¶</a> </div> </div> </li> <li id="section-152"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-152">¶</a> </div> <p>Run Underscore.js in <em>noConflict</em> mode, returning the <code>_</code> variable to its previous owner. Returns a reference to the Underscore object.</p> </div> <div class="content"><div class='highlight'><pre> _.noConflict = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ root._ = previousUnderscore; <span class="hljs-keyword">return</span> <span class="hljs-keyword">this</span>; };</pre></div></div> </li> <li id="section-153"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-153">¶</a> </div> <p>Keep the identity function around for default iteratees.</p> </div> <div class="content"><div class='highlight'><pre> _.identity = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value)</span> </span>{ <span class="hljs-keyword">return</span> value; };</pre></div></div> </li> <li id="section-154"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-154">¶</a> </div> <p>Predicate-generating functions. Often useful outside of Underscore.</p> </div> <div class="content"><div class='highlight'><pre> _.constant = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(value)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> value; }; }; _.noop = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span></span>{}; _.property = property;</pre></div></div> </li> <li id="section-155"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-155">¶</a> </div> <p>Generates a function for a given object that returns a given property.</p> </div> <div class="content"><div class='highlight'><pre> _.propertyOf = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> obj == <span class="hljs-literal">null</span> ? <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span></span>{} : <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(key)</span> </span>{ <span class="hljs-keyword">return</span> obj[key]; }; };</pre></div></div> </li> <li id="section-156"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-156">¶</a> </div> <p>Returns a predicate for checking whether an object has a given set of <code>key:value</code> pairs.</p> </div> <div class="content"><div class='highlight'><pre> _.matcher = _.matches = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(attrs)</span> </span>{ attrs = _.extendOwn({}, attrs); <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">return</span> _.isMatch(obj, attrs); }; };</pre></div></div> </li> <li id="section-157"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-157">¶</a> </div> <p>Run a function <strong>n</strong> times.</p> </div> <div class="content"><div class='highlight'><pre> _.times = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(n, iteratee, context)</span> </span>{ <span class="hljs-keyword">var</span> accum = <span class="hljs-built_in">Array</span>(<span class="hljs-built_in">Math</span>.max(<span class="hljs-number">0</span>, n)); iteratee = optimizeCb(iteratee, context, <span class="hljs-number">1</span>); <span class="hljs-keyword">for</span> (<span class="hljs-keyword">var</span> i = <span class="hljs-number">0</span>; i < n; i++) accum[i] = iteratee(i); <span class="hljs-keyword">return</span> accum; };</pre></div></div> </li> <li id="section-158"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-158">¶</a> </div> <p>Return a random integer between min and max (inclusive).</p> </div> <div class="content"><div class='highlight'><pre> _.random = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(min, max)</span> </span>{ <span class="hljs-keyword">if</span> (max == <span class="hljs-literal">null</span>) { max = min; min = <span class="hljs-number">0</span>; } <span class="hljs-keyword">return</span> min + <span class="hljs-built_in">Math</span>.floor(<span class="hljs-built_in">Math</span>.random() * (max - min + <span class="hljs-number">1</span>)); };</pre></div></div> </li> <li id="section-159"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-159">¶</a> </div> <p>A (possibly faster) way to get the current timestamp as an integer.</p> </div> <div class="content"><div class='highlight'><pre> _.now = <span class="hljs-built_in">Date</span>.now || <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-keyword">new</span> <span class="hljs-built_in">Date</span>().getTime(); };</pre></div></div> </li> <li id="section-160"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-160">¶</a> </div> <p>List of HTML entities for escaping.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> escapeMap = { <span class="hljs-string">'&'</span>: <span class="hljs-string">'&amp;'</span>, <span class="hljs-string">'<'</span>: <span class="hljs-string">'&lt;'</span>, <span class="hljs-string">'>'</span>: <span class="hljs-string">'&gt;'</span>, <span class="hljs-string">'"'</span>: <span class="hljs-string">'&quot;'</span>, <span class="hljs-string">"'"</span>: <span class="hljs-string">'&#x27;'</span>, <span class="hljs-string">'`'</span>: <span class="hljs-string">'&#x60;'</span> }; <span class="hljs-keyword">var</span> unescapeMap = _.invert(escapeMap);</pre></div></div> </li> <li id="section-161"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-161">¶</a> </div> <p>Functions for escaping and unescaping strings to/from HTML interpolation.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> createEscaper = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(map)</span> </span>{ <span class="hljs-keyword">var</span> escaper = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(match)</span> </span>{ <span class="hljs-keyword">return</span> map[match]; };</pre></div></div> </li> <li id="section-162"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-162">¶</a> </div> <p>Regexes for identifying a key that needs to be escaped</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> source = <span class="hljs-string">'(?:'</span> + _.keys(map).join(<span class="hljs-string">'|'</span>) + <span class="hljs-string">')'</span>; <span class="hljs-keyword">var</span> testRegexp = <span class="hljs-built_in">RegExp</span>(source); <span class="hljs-keyword">var</span> replaceRegexp = <span class="hljs-built_in">RegExp</span>(source, <span class="hljs-string">'g'</span>); <span class="hljs-keyword">return</span> <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(string)</span> </span>{ string = string == <span class="hljs-literal">null</span> ? <span class="hljs-string">''</span> : <span class="hljs-string">''</span> + string; <span class="hljs-keyword">return</span> testRegexp.test(string) ? string.replace(replaceRegexp, escaper) : string; }; }; _.escape = createEscaper(escapeMap); _.unescape = createEscaper(unescapeMap);</pre></div></div> </li> <li id="section-163"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-163">¶</a> </div> <p>If the value of the named <code>property</code> is a function then invoke it with the <code>object</code> as context; otherwise, return it.</p> </div> <div class="content"><div class='highlight'><pre> _.result = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(object, property, fallback)</span> </span>{ <span class="hljs-keyword">var</span> value = object == <span class="hljs-literal">null</span> ? <span class="hljs-keyword">void</span> <span class="hljs-number">0</span> : object[property]; <span class="hljs-keyword">if</span> (value === <span class="hljs-keyword">void</span> <span class="hljs-number">0</span>) { value = fallback; } <span class="hljs-keyword">return</span> _.isFunction(value) ? value.call(object) : value; };</pre></div></div> </li> <li id="section-164"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-164">¶</a> </div> <p>Generate a unique integer id (unique within the entire client session). Useful for temporary DOM ids.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> idCounter = <span class="hljs-number">0</span>; _.uniqueId = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(prefix)</span> </span>{ <span class="hljs-keyword">var</span> id = ++idCounter + <span class="hljs-string">''</span>; <span class="hljs-keyword">return</span> prefix ? prefix + id : id; };</pre></div></div> </li> <li id="section-165"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-165">¶</a> </div> <p>By default, Underscore uses ERB-style template delimiters, change the following template settings to use alternative delimiters.</p> </div> <div class="content"><div class='highlight'><pre> _.templateSettings = { evaluate : <span class="hljs-regexp">/<%([\s\S]+?)%>/g</span>, interpolate : <span class="hljs-regexp">/<%=([\s\S]+?)%>/g</span>, <span class="hljs-built_in">escape</span> : <span class="hljs-regexp">/<%-([\s\S]+?)%>/g</span> };</pre></div></div> </li> <li id="section-166"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-166">¶</a> </div> <p>When customizing <code>templateSettings</code>, if you don’t want to define an interpolation, evaluation or escaping regex, we need one that is guaranteed not to match.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> noMatch = <span class="hljs-regexp">/(.)^/</span>;</pre></div></div> </li> <li id="section-167"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-167">¶</a> </div> <p>Certain characters need to be escaped so that they can be put into a string literal.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> escapes = { <span class="hljs-string">"'"</span>: <span class="hljs-string">"'"</span>, <span class="hljs-string">'\\'</span>: <span class="hljs-string">'\\'</span>, <span class="hljs-string">'\r'</span>: <span class="hljs-string">'r'</span>, <span class="hljs-string">'\n'</span>: <span class="hljs-string">'n'</span>, <span class="hljs-string">'\u2028'</span>: <span class="hljs-string">'u2028'</span>, <span class="hljs-string">'\u2029'</span>: <span class="hljs-string">'u2029'</span> }; <span class="hljs-keyword">var</span> escaper = <span class="hljs-regexp">/\\|'|\r|\n|\u2028|\u2029/g</span>; <span class="hljs-keyword">var</span> escapeChar = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(match)</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-string">'\\'</span> + escapes[match]; };</pre></div></div> </li> <li id="section-168"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-168">¶</a> </div> <p>JavaScript micro-templating, similar to John Resig’s implementation. Underscore templating handles arbitrary delimiters, preserves whitespace, and correctly escapes quotes within interpolated code. NB: <code>oldSettings</code> only exists for backwards compatibility.</p> </div> <div class="content"><div class='highlight'><pre> _.template = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(text, settings, oldSettings)</span> </span>{ <span class="hljs-keyword">if</span> (!settings && oldSettings) settings = oldSettings; settings = _.defaults({}, settings, _.templateSettings);</pre></div></div> </li> <li id="section-169"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-169">¶</a> </div> <p>Combine delimiters into one regular expression via alternation.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> matcher = <span class="hljs-built_in">RegExp</span>([ (settings.escape || noMatch).source, (settings.interpolate || noMatch).source, (settings.evaluate || noMatch).source ].join(<span class="hljs-string">'|'</span>) + <span class="hljs-string">'|$'</span>, <span class="hljs-string">'g'</span>);</pre></div></div> </li> <li id="section-170"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-170">¶</a> </div> <p>Compile the template source, escaping string literals appropriately.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> index = <span class="hljs-number">0</span>; <span class="hljs-keyword">var</span> source = <span class="hljs-string">"__p+='"</span>; text.replace(matcher, <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(match, escape, interpolate, evaluate, offset)</span> </span>{ source += text.slice(index, offset).replace(escaper, escapeChar); index = offset + match.length; <span class="hljs-keyword">if</span> (<span class="hljs-built_in">escape</span>) { source += <span class="hljs-string">"'+\n((__t=("</span> + <span class="hljs-built_in">escape</span> + <span class="hljs-string">"))==null?'':_.escape(__t))+\n'"</span>; } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (interpolate) { source += <span class="hljs-string">"'+\n((__t=("</span> + interpolate + <span class="hljs-string">"))==null?'':__t)+\n'"</span>; } <span class="hljs-keyword">else</span> <span class="hljs-keyword">if</span> (evaluate) { source += <span class="hljs-string">"';\n"</span> + evaluate + <span class="hljs-string">"\n__p+='"</span>; }</pre></div></div> </li> <li id="section-171"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-171">¶</a> </div> <p>Adobe VMs need the match returned to produce the correct offset.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">return</span> match; }); source += <span class="hljs-string">"';\n"</span>;</pre></div></div> </li> <li id="section-172"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-172">¶</a> </div> <p>If a variable is not specified, place data values in local scope.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (!settings.variable) source = <span class="hljs-string">'with(obj||{}){\n'</span> + source + <span class="hljs-string">'}\n'</span>; source = <span class="hljs-string">"var __t,__p='',__j=Array.prototype.join,"</span> + <span class="hljs-string">"print=function(){__p+=__j.call(arguments,'');};\n"</span> + source + <span class="hljs-string">'return __p;\n'</span>; <span class="hljs-keyword">try</span> { <span class="hljs-keyword">var</span> render = <span class="hljs-keyword">new</span> <span class="hljs-built_in">Function</span>(settings.variable || <span class="hljs-string">'obj'</span>, <span class="hljs-string">'_'</span>, source); } <span class="hljs-keyword">catch</span> (e) { e.source = source; <span class="hljs-keyword">throw</span> e; } <span class="hljs-keyword">var</span> template = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(data)</span> </span>{ <span class="hljs-keyword">return</span> render.call(<span class="hljs-keyword">this</span>, data, _); };</pre></div></div> </li> <li id="section-173"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-173">¶</a> </div> <p>Provide the compiled source as a convenience for precompilation.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> argument = settings.variable || <span class="hljs-string">'obj'</span>; template.source = <span class="hljs-string">'function('</span> + argument + <span class="hljs-string">'){\n'</span> + source + <span class="hljs-string">'}'</span>; <span class="hljs-keyword">return</span> template; };</pre></div></div> </li> <li id="section-174"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-174">¶</a> </div> <p>Add a “chain” function. Start chaining a wrapped Underscore object.</p> </div> <div class="content"><div class='highlight'><pre> _.chain = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ <span class="hljs-keyword">var</span> instance = _(obj); instance._chain = <span class="hljs-literal">true</span>; <span class="hljs-keyword">return</span> instance; };</pre></div></div> </li> <li id="section-175"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-175">¶</a> </div> <h2 id="oop">OOP</h2> </div> </li> <li id="section-176"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-176">¶</a> </div> <p>If Underscore is called as a function, it returns a wrapped object that can be used OO-style. This wrapper holds altered versions of all the underscore functions. Wrapped objects may be chained.</p> </div> </li> <li id="section-177"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-177">¶</a> </div> <p>Helper function to continue chaining intermediate results.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">var</span> result = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(instance, obj)</span> </span>{ <span class="hljs-keyword">return</span> instance._chain ? _(obj).chain() : obj; };</pre></div></div> </li> <li id="section-178"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-178">¶</a> </div> <p>Add your own custom functions to the Underscore object.</p> </div> <div class="content"><div class='highlight'><pre> _.mixin = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(obj)</span> </span>{ _.each(_.functions(obj), <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(name)</span> </span>{ <span class="hljs-keyword">var</span> func = _[name] = obj[name]; _.prototype[name] = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">var</span> args = [<span class="hljs-keyword">this</span>._wrapped]; push.apply(args, <span class="hljs-built_in">arguments</span>); <span class="hljs-keyword">return</span> result(<span class="hljs-keyword">this</span>, func.apply(_, args)); }; }); };</pre></div></div> </li> <li id="section-179"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-179">¶</a> </div> <p>Add all of the Underscore functions to the wrapper object.</p> </div> <div class="content"><div class='highlight'><pre> _.mixin(_);</pre></div></div> </li> <li id="section-180"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-180">¶</a> </div> <p>Add all mutator Array functions to the wrapper.</p> </div> <div class="content"><div class='highlight'><pre> _.each([<span class="hljs-string">'pop'</span>, <span class="hljs-string">'push'</span>, <span class="hljs-string">'reverse'</span>, <span class="hljs-string">'shift'</span>, <span class="hljs-string">'sort'</span>, <span class="hljs-string">'splice'</span>, <span class="hljs-string">'unshift'</span>], <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(name)</span> </span>{ <span class="hljs-keyword">var</span> method = ArrayProto[name]; _.prototype[name] = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">var</span> obj = <span class="hljs-keyword">this</span>._wrapped; method.apply(obj, <span class="hljs-built_in">arguments</span>); <span class="hljs-keyword">if</span> ((name === <span class="hljs-string">'shift'</span> || name === <span class="hljs-string">'splice'</span>) && obj.length === <span class="hljs-number">0</span>) <span class="hljs-keyword">delete</span> obj[<span class="hljs-number">0</span>]; <span class="hljs-keyword">return</span> result(<span class="hljs-keyword">this</span>, obj); }; });</pre></div></div> </li> <li id="section-181"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-181">¶</a> </div> <p>Add all accessor Array functions to the wrapper.</p> </div> <div class="content"><div class='highlight'><pre> _.each([<span class="hljs-string">'concat'</span>, <span class="hljs-string">'join'</span>, <span class="hljs-string">'slice'</span>], <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">(name)</span> </span>{ <span class="hljs-keyword">var</span> method = ArrayProto[name]; _.prototype[name] = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> result(<span class="hljs-keyword">this</span>, method.apply(<span class="hljs-keyword">this</span>._wrapped, <span class="hljs-built_in">arguments</span>)); }; });</pre></div></div> </li> <li id="section-182"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-182">¶</a> </div> <p>Extracts the result from a wrapped and chained object.</p> </div> <div class="content"><div class='highlight'><pre> _.prototype.value = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-keyword">this</span>._wrapped; };</pre></div></div> </li> <li id="section-183"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-183">¶</a> </div> <p>Provide unwrapping proxy for some methods used in engine operations such as arithmetic and JSON stringification.</p> </div> <div class="content"><div class='highlight'><pre> _.prototype.valueOf = _.prototype.toJSON = _.prototype.value; _.prototype.toString = <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> <span class="hljs-string">''</span> + <span class="hljs-keyword">this</span>._wrapped; };</pre></div></div> </li> <li id="section-184"> <div class="annotation"> <div class="pilwrap "> <a class="pilcrow" href="#section-184">¶</a> </div> <p>AMD registration happens at the end for compatibility with AMD loaders that may not enforce next-turn semantics on modules. Even though general practice for AMD registration is to be anonymous, underscore registers as a named module because, like jQuery, it is a base library that is popular enough to be bundled in a third party lib, but not be part of an AMD load request. Those cases could generate an error when an anonymous define() is called outside of a loader request.</p> </div> <div class="content"><div class='highlight'><pre> <span class="hljs-keyword">if</span> (<span class="hljs-keyword">typeof</span> define === <span class="hljs-string">'function'</span> && define.amd) { define(<span class="hljs-string">'underscore'</span>, [], <span class="hljs-function"><span class="hljs-keyword">function</span><span class="hljs-params">()</span> </span>{ <span class="hljs-keyword">return</span> _; }); } }.call(<span class="hljs-keyword">this</span>));</pre></div></div> </li> </ul> </div> </body> </html>