How do you detect that a script was loaded *and* executed in a chrome extension? -

i've been tracking down bug days... realized bug me. :/

i had been using webrequest.oncomplete, filtered scripts. error made incorrect association between scripts being loaded , being executed. loaded in different order executed, , timing of events not in order need them in. need inject between scripts need event right after file has been executed , before next one.

the solution can think of @ moment alter js being loaded before gets executed. makes stomach turn. , bfcache wreak more havoc, not great solution either.

i use html5 spec's afterscriptexecute, not implemented in chrome. there api, perhaps extension api can use?

note: method no longer works of chrome 36. there no direct alternatives.

^{note: answer below applies external scripts, i.e. loaded <script src>.}

in chrome (and safari), "beforeload" event triggered right before resource loaded. event allows 1 block resource, script never fetched. in event, can determine whether loaded resource script, , check whether want perform action

this event can used emulate beforescriptexecute / afterscriptexecute:

document.addeventlistener('beforeload', function(event) {     var target = event.target;     if (target.nodename.touppercase() !== 'script') return;     var dispatchevent = function(name, bubbles, cancelable) {         var evt = new customevent(name, {             bubbles: bubbles,             cancelable: cancelable         });         target.dispatchevent(evt);         if (evt.defaultprevented) {             event.preventdefault();         }     };     var onload = function() {         cleanup();         dispatchevent('afterscriptexecute', true, false);     };     var cleanup = function() {         target.removeeventlistener('load', onload, true);         target.removeeventlistener('error', cleanup, true);     }     target.addeventlistener('error', cleanup, true);     target.addeventlistener('load', onload, true);      dispatchevent('beforescriptexecute', true, true); }, true); 

the dispatch times not 100% identical original ones, sufficient cases. time line (non-emulated) events:

beforeload             before network request started beforescriptexecute    before script executes afterscriptexecute     after script executes onload                 after script has executed 

here's easy way see events working expected:

window.addeventlistener('afterscriptexecute', function() {     alert(window.x); }); document.head.appendchild(document.createelement('script')).src = 'data:,x=1'; document.head.appendchild(document.createelement('script')).src = 'data:,x=2'; 

the demo can seen live @ http://jsfiddle.net/sdazt/