在javascript中设置对象 [英] Set of objects in javascript

问题描述

我想在Javascript中有一组对象。也就是说，一个仅包含唯一对象的数据结构。

建议使用属性。 myset [key] = true 。但是，我需要的键是对象。我已经看到Javascript将属性名称转换为字符串，所以我想我不能使用 myset [myobject] = true 。

我可以使用数组，但是我需要比O（n）性能更好的添加，查找和删除项目。

它需要能够通过参考来分开对象，所以给出：

  var a = {}; 
 var b = {}; 
  

然后两者 a 和 b 应该可以添加，因为它们是单独的对象。

基本上，我的东西像C ++的code> std :: set ，可以存储Javascript对象。任何想法？

解决方案

ES6提供了一个本地地图：

  let m = new Map（）; 
 let a = {}; 
 let b = {}; 
 
 m.set（a，b）; 
 m.set（b，10）; 
 
 m.get（m.get（a））// 10 
  

这是一个很久以前我已经有一个接近自然的结构，你可以得到：

 功能映射（ ）{
 var keys = []; 
 var values = []; 
 
函数get（key）{
 var i = keys.indexOf（key）; 
 return i === -1？ null：values [i]; 
} 
 
 get.set =函数集（key，value）{
 var i = keys.indexOf（key）; 
 
 if（i === -1）{
 keys.push（key）; 
 values.push（value）; 
} else {
 values [i] = value; 
} 
}; 
 
 return get; 
} 
  

使用它像这样：

  var m = map（）; 
 var a = {}; 
 var b = {}; 
 
 m.set（a，b）; 
 m.set（b，10）; 
 
 m（m（a））; // 10 
  

要删除一个值，只需使用 x.set（whateverKey ，null）因为它没有找到钥匙时返回null，所以没有区别。

I'd like to have a set of objects in Javascript. That is, a data structure that contains only unique objects.

Normally using properties is recommended, e.g. myset["key"] = true. However, I need the keys to be objects. I've read that Javascript casts property names to strings, so I guess I can't use myset[myobject] = true.

I could use an array, but I need something better than O(n) performance for adding, finding and removing items.

It needs to be able to tell objects apart by reference only, so given:

var a = {};
var b = {};

then both a and b should be able to be added, because they're separate objects.

Basically, I'm after something like C++'s std::set, that can store Javascript objects. Any ideas?

解决方案

ES6 provides a native Map:

let m = new Map();
let a = {};
let b = {};

m.set(a, b);
m.set(b, 10);

m.get(m.get(a))  // 10

Here's one I have from a long time ago that is about as close to natural structure as you can get:

function map() {
    var keys = [];
    var values = [];

    function get(key) {
        var i = keys.indexOf(key);
        return i === -1 ? null : values[i];
    }

    get.set = function set(key, value) {
        var i = keys.indexOf(key);

        if (i === -1) {
            keys.push(key);
            values.push(value);
        } else {
            values[i] = value;
        }
    };

    return get;
}

Use it like so:

var m = map();
var a = {};
var b = {};

m.set(a, b);
m.set(b, 10);

m(m(a));  // 10

To remove a value, just use x.set(whateverKey, null) because it returns null when the key is not found so there is no difference.

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