JS: Deferred, asynchronous script loading

async-script.js

<script type="text/javascript">
	// Add a script element as a child of the body
	function downloadJSAtOnload() {
		var script = document.createElement("script");
		script.src = "script.js";
		document.body.appendChild(script);
	}

	// Check for browser support of event handling capability
	if (window.addEventListener) {
		window.addEventListener("load", downloadJSAtOnload, false);
	} else if (window.attachEvent) {
	 	window.attachEvent("onload", downloadJSAtOnload);
	} else {
		window.onload = downloadJSAtOnload;
	}
</script>