在JavaScript中提升变量 [英] Hoisting variables in JavaScript

问题描述

我理解变量的提升是在Java Script中完成的。我无法理解为什么输出为未定义

I understand Hoisting of variables is done in Java Script. I am unable to get why it outputs as undefined

 do_something()
    {
    var foo = 2;    
    console.log(foo);   
    } do_something()  // it prints 2

 do_something()
     {        
     console.log(foo);  var foo = 2;  
     } do_something()  // it prints undefined

因为javascript也提升第二个函数应该按照我的理解打印2。购买为什么不呢

As javascript do hoisting the second function also should print 2 as per my understand.buy why doesn't it

推荐答案

只有声明被悬挂。分配的变量不会被提升。所以你

Only the declaration is hoisted. the assigned variables are not hoisted. So you are

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