lazy load js

lazyload.js

// can be used for JSONP calls too
var loadScript = function(url, callback) {
	var script = document.createElement('script');
	script.setAttribute('src', url);
	script.setAttribute("type","text/javascript");
	script.setAttribute('async', true);
	// wait for script to load
	var onLoaded = function(script,callback) {
		return function() {
			// remove the script
			document.getElementsByTagName('head')[0].removeChild(script);
			// run any callback
			if (callback) {
				callback();
			}
		}
	}
	if (document.addEventListener) {
	  script.addEventListener('load',onLoaded(script,callback), false);
	} else {
	  elem.attachEvent('onreadystatechange', function () {
		if (elem.readyState == 'loaded' || elem.readyState == 'complete') {
			onLoaded(script,callback)();
		}
	  });
	}
	document.getElementsByTagName('head')[0].appendChild(script);
}