Firefox和Node.js之间的解释差异 [英] Difference in interpretation between Firefox and Node.js

问题描述

我遇到了Firefox和Node.js之间的异常。给出以下代码：

 'use strict'; 
 const obj = {}; 
 for（let f of ['left'，'right']）{
 obj [f] = function（）{
 return f; 
}; 
} 
 console.log（obj.left（））; 
 console.log（obj.right（））; 
  

Firefox（48.0）输出

  right 
 right 
  

而Node.js（6.4。 0）输出

  left 
 right 
  

都在Ubuntu 14.04上。我没有可能用其他ECMAScript引擎进行测试。

任何想法有什么区别的原因，哪些实现对规范是正确的？

解决方案

您的Node版本正确， let code> for loop应该有块范围。

FF 48 根本不支持for / in-in循环遍历范围，它似乎用FF 51修复。

I have come across an anomaly between Firefox and Node.js. Given the following code:

'use strict';
const obj = {};
for (let f of ['left', 'right']) {
  obj[f] = function() {
    return f;
  };
}
console.log(obj.left());
console.log(obj.right());

Firefox (48.0) outputs

right
right

while Node.js (6.4.0) outputs

left
right

Both on Ubuntu 14.04. I didn't have the possibility to test with other ECMAScript engines.

Any idea what is the reason for the difference, and which implementation is correct with respect to the specification?

解决方案

Your version of Node is correct here, let in a for loop should have block scope.

FF 48 simply doesn't support "for/for-in loop iteration scope" yet, it appears to be fixed with FF 51.

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