chrome.webRequest.onBeforeSendHeaders.addListener(function(details) { var newxff = (Math.floor((Math.random()*100000000))).toString(); var gotxff = false; for(var n in details.requestHeaders){ gotxff = details.requestHeaders[n].name.toLowerCase()=="x-forwarded-for"; if(gotxff){ details.requestHeaders[n].value = newxff; break; } } if(!gotxff){ details.requestHeaders.push({name:"X-Forwarded-For",value:newxff}); } console.log(details); return { requestHeaders: details.requestHeaders }; }, { urls: ['*://*.slader.com/*'] }, ['blocking', 'requestHeaders']); chrome.webRequest.onSendHeaders.addListener(function(details) { console.log(details.requestHeaders); return { requestHeaders: details.requestHeaders }; }, {urls: ['*://*.slader.com/textbook/*']}, ['requestHeaders']);