loadJs.js

/**
 *  refer:easyloader.js
 */
function loadJs(url, callback){
	var done = false;
	var script = document.createElement('script');
	script.type = 'text/javascript';
	script.language = 'javascript';
	script.src = url;
	script.onload = script.onreadystatechange = function(){
		if (!done && (!script.readyState || script.readyState == 'loaded' || script.readyState == 'complete')){
			done = true;
			script.onload = script.onreadystatechange = null;
			if (callback){
				callback.call(script);
			}
		}
	}
	document.getElementsByTagName("head")[0].appendChild(script);
}

function runJs(url, callback){
	loadJs(url, function(){
		document.getElementsByTagName("head")[0].removeChild(this);
		if (callback){
			callback();
		}
	});
}