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Day9：写出执行结果,并解释原因 #45

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Day9：写出执行结果,并解释原因#45
@Genzhen

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@Genzhen
Genzhen
opened on Jun 22, 2020 · edited by Genzhen
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var foo = function bar(){ return 12; };
console.log(typeof bar());  
// 写出执行结果，并解释原因

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Genzhen

Genzhen commented on Jun 22, 2020

@Genzhen
Genzhen
on Jun 22, 2020
CollaboratorAuthor

答案
输出是抛出异常，bar is not defined。

解析
这种命名函数表达式函数只能在函数体内有效

var foo = function bar(){ 
    // foo is visible here 
    // bar is visible here
    console.log(typeof bar()); // Work here :)
};
// foo is visible here
// bar is undefined here
Dannyzn

Dannyzn commented on Jul 19, 2020

@Dannyzn
Dannyzn
on Jul 19, 2020
typeof(bar). // "undefined"
typeof(foo()). // "number"
typeof(foo).   // "function"
typeof(bar()). // VM5167:1 Uncaught ReferenceError: bar is not defined
Genzhen
closed this as completedon Jul 20, 2020
Genzhen
reopened this on Jul 29, 2020
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          Day9：写出执行结果,并解释原因 · Issue #45 · lgwebdream/FE-Interview