在JS中查找对象的特定值的键 [英] Find key for specific value on object in JS

问题描述

我有一个这样的对象，它是使用lodash的 _.zipObject()函数生成的.所以我有2个数组，一个是位置，一个是数字.

I have an object as such that has been generated by using the lodash _.zipObject() function. So I have 2 arrays, one of locations, one of numbers.

var locs = {'Aberdeen': 304, 'Aberystwith': 109, 'Belfast': 219, 'Birmingham': 24, 'Brighton': 147, …}

我需要根据输入值返回键.例如， function(304)将返回'Aberdeen'.

I need to return the key based on an input value. For example, function(304) would return 'Aberdeen'.

我已经尝试过 _.findkey(locs，304); ，但这只会返回未定义的内容.我尝试过的任何其他尝试总是返回undefined或-1.不太确定从这里去哪里.

I've tried _.findkey(locs, 304); but this just returns undefined. Any other attempt I've tried always returns either undefined or -1. Not really sure where to go from here.

推荐答案

要查找键，请使用带有 _.findKey() :

To find the key use a predicate function with _.findKey():

var locs = {'Aberdeen': 304, 'Aberystwith': 109, 'Belfast': 219, 'Birmingham': 24, 'Brighton': 147 };

var key = _.findKey(locs, function(v) {
  return v === 304;
});

console.log(key);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

您可以通过使用所请求的值使用 _.eq()来创建谓词:

You can create the predicate by currying _.eq() with the requested value:

var locs = {'Aberdeen': 304, 'Aberystwith': 109, 'Belfast': 219, 'Birmingham': 24, 'Brighton': 147 };

var key = _.findKey(locs, _.curry(_.eq, 304));

console.log(key);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

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