使用Array对象作为ES6 Map的键 [英] Using Array objects as key for ES6 Map

问题描述

我正在尝试将我的代码更新为ES6，因为我使用的是Node 4.0，并且到目前为止它非常喜欢它的功能。但是我在新的ES6 Map 数据结构时遇到问题，因为当使用<$ c $时，它与 {} 的行为不同c>数组作为密钥。我使用它作为计数器地图。

I am trying to update my code to ES6 as I am using Node 4.0 and really like its features so far. However I have problems with the new ES6 Map data structure as it behaves differently to {} when using Array as a key. I am using it as a counter map.

我运行此代码，我想知道如何使用数组作为地图的键。

I run this code and I would like to know how I can use arrays as keys for the Map.

"use strict";

var a = new Map();
a.set(['x','y'], 1);
console.log(a.get(['x','y']));

var b = {};
b[['x','y']] = 1;

console.log(b[['x','y']]);

打印出以下内容，第一行应为 1 而不是未定义：

It prints out the following and the first line should be 1 and not undefined:

undefined
1

原始的JS地图将字符串化，我不想做同样类型的stringify hack使用新的ES6 地图。

The original JS map stringifies the key and I am not wanting to do the same type of stringify hack with the new ES6 Map.

如何将数组作为密钥可靠地用于ES6 Map ？

What can I do to use arrays as keys reliably for a ES6 Map?

推荐答案

了解ES2015 Map键与 === 运算符进行比较。两个数组实例，即使它们包含相同的值，也不会相互比较为 === 。

Understand that ES2015 Map keys are compared as if with the === operator. Two array instances, even if they contain the same values, do not ever compare as === to each other.

试试这个：

var a = new Map(), key = ['x', 'y'];
a.set(key, 1);
console.log(a.get(key));

由于Map类可用作基类，因此可以实现一个子类，覆盖 .get（）函数，也许。

Since the Map class is intended to be usable as a base class, you could implement a subclass with an overriding .get() function, maybe.

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