为什么使用数组作为键来访问对象中的元素? [英] Why does accessing an element in an object using an array as a key work?

问题描述

您对此有何看法?

var x = {a: 1};         //=> {a: 1}
var y = Object.keys(x); //=> ['a']
x[y]                    //=> 1

如果 y = ['a'] ，则 x [y] 与执行 x [['a']] 相同，对吧?

if y = ['a'], x[y] is the same as doing x[['a']], right?

x[['a']];               //=> 1

x[[['a']]];             //=> 1

x[[[[[[[['a']]]]]]]];   //=> 1

有人可以解释这里发生了什么吗?为什么这样做有效?

Can someone explain what's happening here? Why does this work?

推荐答案

@Quentin建议将属性名称自动转换为字符串.好的，我认为他在这里，但是给出两个显式的 arr.toString()示例并没有真正演示如何使用数组访问对象的属性.我将此内容作为对他帖子的修改.但是，他回滚了.

@Quentin suggests that property names are automatically converted to strings. Ok, I think he's onto something there, but giving two explicit arr.toString() examples doesn't really demonstrate accessing the property of an object using an array. I offered this as an edit to his post. However, he rolled it back.

无论如何，这更明显地证明了隐式行为，imo.

Anyway, this demonstrates the implicit behavior much more evidently, imo.

var x = {'a,b,c': 1};

var y = ['a','b','c'];

x[y]; //=> 1

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