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。