方法一、

function loadScript(url, callback){

callback=callback||function(){};

var script = document.createElement("script")

script.type = "text/javascript";

if (script.readyState){  //IE

script.onreadystatechange = function(){

if (script.readyState == "loaded" ||

script.readyState == "complete"){

script.onreadystatechange = null;

callback();

}

};

} else {  //Others: Firefox, Safari, Chrome, and Opera

script.onload = function(){

callback();

};

}

script.src = url;

document.body.appendChild(script);

} 

 使用時(shí)，只要簡(jiǎn)單地傳遞JavaScript文件的URL和回調(diào)函數(shù)即可：

loadScript("http://yui./2.7.0/build/yahoo/yahoo-min.js",

function(){

YAHOO.namespace("mystuff");

//more...

});

方法二可以跨域加載JS文件:

var MiniSite=new Object();

MiniSite.Browser={

ie:/msie/.test(window.navigator.userAgent.toLowerCase()),

moz:/gecko/.test(window.navigator.userAgent.toLowerCase()),

opera:/opera/.test(window.navigator.userAgent.toLowerCase()),

safari:/safari/.test(window.navigator.userAgent.toLowerCase())

};

MiniSite.JsLoader={

load:function(sUrl,fCallback){

fCallback=fCallback||function(){};

var _script=document.createElement('script');

_script.setAttribute('type','text/javascript');

_script.setAttribute('src',sUrl);

document.getElementsByTagName('head')[0].appendChild(_script);

if(MiniSite.Browser.ie){

_script.onreadystatechange=function(){

if(this.readyState=='loaded'||this.readyState=='complete'){

fCallback();

}

};

}else if(MiniSite.Browser.moz){

_script.onload=function(){

fCallback();

};

}else{

fCallback();

}

}

};

使用方法：

//使用方法

function showaddr()

{

alert(IPData);

}

MiniSite.JsLoader.load("http://fw.qq.com/ipaddress",function(){showaddr();});