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javascript定义变量时加var与不加var的区别_基础知识

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Release： 2016-05-16 16:25:21
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一、外部的为全局，内部的为局部变量。

二、加var为局部变量(在方法内)，不加var为全局变量(当方法内有一次使用后)

复制代码 代码如下:


在上面的test方法内，当把local变量的var去掉后，local就变成了全局变量，但是在局部不使用local，则这个local作为全局是无效的。

为了验证这点，我把test方法内部唯一使用local变量的这句代码注释掉.发现在外部也打印不出来了。

总结：全局变量可以不声明var 函数内变量必须声明var，在定义全局变量时加或不加var关键字没什么影响；但在定义局部变量时如果不加var关键字javascript解释程序会将其解释为全局变量。

Related labels：
javascript var
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