Facebook的图书馆的keyMirror节点包的使用是什么？ [英] what is the use of the keyMirror node package part of facebook's library?

问题描述

这是在这里找到的关键镜像包
https://www.npmjs.com/package / keymirror

它将其定义为创建一个值等于其键值的对象的简单实用程序

输入：{key1：val1，key2：val2}
输出：{key1：key1，key2：key2}

但是为什么我需要这样做？

p>

  {OPTION_ONE：1，OPTION_TWO：2，OPTION_THREE：3} 
  

为什么一个应用程序会发现以下转换对上述输入有用？

  {OPTION_ONE：OPTION_ONE，OPTION_TWO：OPTION_TWO，OPTION_THREE：OPTION_THREE} 
  

解决方案>

它正在制作一个Enum对象（ https://en.wikipedia.org/wiki/Enumerated_type）

$ b $你可以这样做，就像你所说的 {OPTION_ONE：1，OPTION_TWO：2，OPTION_THREE：3} ，这是一个类似的枚举对象，但是如果你想知道值 6 是否是枚举中的值？你必须循环所有的键并检查所有的值。

但是，如果键和值匹配，那么您只需检查对象中是否存在键，以知道该值是否也可以。

  var mirror = keyMirror（{a：null，b：null}）; 
 var someValue ='d'; 
 var validValue = mirror [someValue]！== undefined; 
  

This is the keyMirror package found here https://www.npmjs.com/package/keymirror

it defines it as A simple utility for creating an object with values equal to its keys

Input: {key1: val1, key2: val2}
Output: {key1: key1, key2: key2}

But why would i need to do this?

how is this different from say,

{OPTION_ONE:1, OPTION_TWO:2, OPTION_THREE:3}

Why would an application find the below transformation to the above input useful?

{OPTION_ONE:OPTION_ONE, OPTION_TWO:OPTION_TWO, OPTION_THREE:OPTION_THREE}

解决方案

It's making an Enum object (https://en.wikipedia.org/wiki/Enumerated_type)

You could do, like you said {OPTION_ONE:1, OPTION_TWO:2, OPTION_THREE:3}, which is a similar Enum object, but what if you wanted to know if the value 6 was a value from the enum? You would have to loop over all the keys and check all the values.

But, if the keys and values match, then you can just check if the key exists in the object to know if the value also does.

var mirror = keyMirror({a: null, b:null});
var someValue = 'd';
var validValue = mirror[someValue] !== undefined;

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