用GET方式装入并执行一个远程JavaScript文件。

注意：Safari在2.0.x或以下版本脚本不能全局内容同步，如果你通过getScript装入一个函数，请确信延迟正确装入后调用。

返回值：XMLHttpRequest

参数：

• url (String): 装入页面的URL地址
• callback (Function): （可选） 当数据装入完成时执行的函数.

示例：

$.getScript("test.js");

示例：

$.getScript("test.js",
   function(){
     alert("Script loaded   and executed.");
   }
); 

Loads, and executes, a remote JavaScript file using an HTTP GET request.

Warning: Safari <= 2.0.x is unable to evaluate scripts in a global context synchronously. If you load functions via getScript, make sure to call them after a delay.

Return value: XMLHttpRequest
Parameters:

• url (String): The URL of the page to load.
• callback (Function): (optional) A function to be executed whenever the data is loaded successfully.

Example:

 $.getScript("test.js");  

Example:

 $.getScript("test.js",
   function(){
     alert("Script loaded and executed.");
   }
 );