Javascript executes twice in Internet Explorer

Question

I currently ran into a problem where a lazy loaded javascript would execute twice using internet explorer - and ONLY internet explorer (currently version 9). Firefox and chrome works. Here is my code:

injectExternalJavaScript: function(fileUrl) {
    return jQuery.Deferred(function(deferred) {
        var script = document.createElement('script');
        script['src'] = fileUrl;
        script['type'] = 'text/javascript';
        var head = document.getElementsByTagName("head")[0];
        var done = false;
        // Attach handlers for all browsers
        script['onload'] = script['onreadystatechange'] = function() {
            if (!done && (!this.readyState || this.readyState === "loaded" || this.readyState === 'complete')) {
                done = true;
                script['onload'] = script['onreadystatechange'] = null;
                head.removeChild(script);
                deferred.resolve();
            }
        };
        head.appendChild(script);
    }).promise();
}

I already found this posting and changed my code according to it but still ie is executing my script twice. You guys got any ideas?

Edit: This is my solution

injectExternalJavaScript: function(fileUrl) {
    return jQuery.Deferred(function(deferred) {
        var script = document.createElement('script');
        script['src'] = fileUrl;
        script['type'] = 'text/javascript';
        var head = document.getElementsByTagName("head")[0];
        var done = false;
        // Attach handlers for all browsers
        var cb = function() {
            if (!done && (!this.readyState || this.readyState === "loaded" || this.readyState === 'complete')) {
                done = true;
                script['onload'] = script['onreadystatechange'] = null;
                head.removeChild(script);
                deferred.resolve();
            }
        }
        if (script.addEventListener) {
            script.addEventListener('load', cb, false);
        } else {
            script['onreadystatechange'] = cb;
        }
        head.appendChild(script);
    }).promise();
}

Answer 1

Try this

s = document.createElement("script");
s.src="myscript.js";
if(s.addEventListener) {
    s.addEventListener("load",callback,false);
}else if(s.readyState) {
    s.onreadystatechange = callback;
}
document.body.appendChild(s);
function callback() { console.log("loaded"); }

taken from http://msdn.microsoft.com/en-us/library/ie/hh180173(v=vs.85).aspx

which for you would be...

injectExternalJavaScript: function(fileUrl) {
    return jQuery.Deferred(function(deferred) {
        var script = document.createElement('script');
        script['src'] = fileUrl;
        script['type'] = 'text/javascript';
        var head = document.getElementsByTagName("head")[0];
        var done = false;
        // Attach handlers for all browsers
        var cb = function() {
            if (!done && (!this.readyState || this.readyState === "loaded" || this.readyState === 'complete')) {
                done = true;
                script['onload'] = script['onreadystatechange'] = null;
                head.removeChild(script);
                deferred.resolve();
            }
        };
        if ( script.addEventListener ) {
            script.addEventListener('load',cb, false);
        } else {
            script.onreadystatechange = cb;
        }
        head.appendChild(script);
    }).promise();
}