Async Third party script loader after body.onload

AsyncOnload3rdPartyScriptLoader.js

<script>
	// Credit to:
	// Original function adapted from Facebook async script at - http://www.phpied.com/social-button-bffs/
	// http://twitter.com/aaronpeters
	// http://www.aaronpeters.nl/blog/why-loading-third-party-scripts-async-is-not-good-enough
        (function(w, d, s) {
		function go(){
			var js, fjs = d.getElementsByTagName(s)[0], load = function(url, id, cb) {
			if (d.getElementById(id)) {return;}
			js = d.createElement(s); js.src = url; js.id = id;
			fjs.parentNode.insertBefore(js, fjs);

			// if callback, execute the callback.
			if (typeof cb === 'function') {
				js.onload = cb.call(this, id);
				// For IE
				js.onreadystatechange = function (id) {             
					if (this.readyState === 'complete' || this.readyState === 'loaded') {
						cb.call(this, id);
					}
				};
			}
		};
		load('//connect.facebook.net/en_US/all.js', 'fbjssdk', false);
		// Uncomment the following for Google or Twitter
                //load('https://apis.google.com/js/plusone.js', 'gplus1js', false);
		//load('//platform.twitter.com/widgets.js', 'tweetjs', false);
	}
	if (w.addEventListener) { w.addEventListener("load", go); }
	else if (w.attachEvent) { w.attachEvent("onload",go); }
	}(window, document, 'script'));	
</script>

Works fine, but "scriptLoadedCallback" function isn't defined and callbacks don't work.

You have to define the callback function separately, see the comment a couple lines up: The function needs to be created seperately or it will error.

I should update this though, rather than pass true/false for the cb var, and call a function called scriptLoadedCallback, I just pass the callback itself.