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8. 作用域、作用域链、闭包 #8

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maxlxq opened this issue Dec 10, 2019 · 0 comments

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maxlxq commented Dec 10, 2019 •

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作用域
在JS中，分为全局作用域和局部作用域。
全局作用域中的全局变量能被任何函数或方法访问，在JavaScript中默认是可以被修改的。
局部作用域包括函数作用域、块级作用域。

作用域链
如果一个变量在当前作用域中使用，当前作用域未找到变量的定义，就会向父级作用域寻找，依次向父级寻找，找到则直接供当前作用域使用，未找到则抛出异常ReferenceError

闭包

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