### 返回值:jQueryunload([[data],fn])
### 概述
在当用户离开页面时，会发生 unload 事件。
具体来说，当发生以下情况时，会发出 unload 事件：
- 点击某个离开页面的链接
- 在地址栏中键入了新的 URL
- 使用前进或后退按钮
- 关闭浏览器
- 重新加载页面
### 参数
#### **fn**Function*V1.0*
在每一个匹配元素的unload事件中绑定的处理函数。
#### **[data],fn**String,Function*V1.4.3*
**data**:unload([Data], fn) 可传入data供函数fn处理。
**fn**:在每一个匹配元素的unload事件中绑定的处理函数。
### 示例
#### 描述:
页面卸载的时候弹出一个警告框:
##### jQuery 代码:
~~~
$(window).unload( function () { alert("Bye now!"); } );
~~~
- 速查表
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- 效果
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