本文实例讲述了异步安全加载javascript文件的方法。分享给大家供大家参考。具体如下：

使用方法：

(function() { __safeLoadScript("http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js", function() { alert(jQuery); });})();

JavaScript实现代码：

window.__safeLoadScript = function(src, callback) { function addEvent(obj, type, fn) { if (obj.attachEvent) { obj['e' + type + fn] = fn; obj[type + fn] = function() { obj['e' + type + fn](window.event); } obj.attachEvent('on' + type, obj[type + fn]); } else obj.addEventListener(type, fn, false); } function async_load(src, callback) { var s = document.createElement('script'); s.type = 'text/javascript'; s.async = true; var protocol = (("https:" == document.location.protocol) ? "https://" : "http://"); s.src = protocol + src; var x = document.getElementsByTagName('script')[0]; x.parentNode.insertBefore(s, x); s.onload = s.onreadystatechange = function() { if(callback && (!this.readyState || this.readyState == "loaded" || this.readyState == "complete")) { callback(); } }; } addEvent(window, "load", function() { async_load(src, callback); });};

希望本文所述对大家的javascript程序设计有所帮助。