通过属性值从对象数组中获取JavaScript对象[重复]

本文翻译自：Get JavaScript object from array of objects by value of property [duplicate]

This question already has an answer here:这个问题已经在这里有了答案：

Find object by id in an array of JavaScript objects 32 answers在JavaScript对象数组中按ID查找对象 32个答案

Let's say I have an array of four objects:假设我有四个对象组成的数组：

var jsObjects = [{a: 1, b: 2}, {a: 3, b: 4}, {a: 5, b: 6}, {a: 7, b: 8}];

Is there a way that I can get the third object ({a: 5, b: 6}) by the value of the propertybfor example without afor...inloop?有没有一种方法可以通过属性b的值获取第三个对象（{a: 5, b: 6}），例如，没有for...in循环？

#1楼

参考：/question/waiJ/通过属性值从对象数组中获取JavaScript对象-重复

#2楼

Filterarray of objects, which property matches value, returns array:Filter对象数组，其属性与值匹配，返回数组：

var result = jsObjects.filter(obj => {return obj.b === 6})

See the MDN Docs on Array.prototype.filter()请参阅Array.prototype.filter（）上的MDN文档

const jsObjects = [ {a: 1, b: 2}, {a: 3, b: 4}, {a: 5, b: 6}, {a: 7, b: 8} ] let result = jsObjects.filter(obj => { return obj.b === 6 }) console.log(result)

Findthe value of the first element/object in the array, otherwiseundefinedis returned.Find数组中第一个元素/对象的值，否则返回undefined。

var result = jsObjects.find(obj => {return obj.b === 6})

See the MDN Docs on Array.prototype.find()请参阅Array.prototype.find（）上的MDN文档

const jsObjects = [ {a: 1, b: 2}, {a: 3, b: 4}, {a: 5, b: 6}, {a: 7, b: 8} ] let result = jsObjects.find(obj => { return obj.b === 6 }) console.log(result)

#3楼

If I understand correctly, you want to find the object in the array whosebproperty is6?如果我理解正确，您想在b属性为6的数组中找到对象。

var found;jsObjects.some(function (obj) {if (obj.b === 6) {found = obj;return true;}});

Or if you were using underscore:或者，如果您使用下划线：

var found = _.select(jsObjects, function (obj) {return obj.b === 6;});

#4楼

I don't know why you are against a for loop (presumably you meant a for loop, not specifically for..in), they are fast and easy to read.我不知道您为什么反对for循环（大概是指for循环，而不是专门针对..in），它们快速且易于阅读。Anyhow, here's some options.无论如何，这里有一些选择。

For loop:对于循环：

function getByValue(arr, value) {for (var i=0, iLen=arr.length; i<iLen; i++) {if (arr[i].b == value) return arr[i];}}

.filter。过滤

function getByValue2(arr, value) {var result = arr.filter(function(o){return o.b == value;} );return result? result[0] : null; // or undefined}

.forEach.for每个

function getByValue3(arr, value) {var result = [];arr.forEach(function(o){if (o.b == value) result.push(o);} );return result? result[0] : null; // or undefined}

If, on the other hand you really did mean for..in and want to find an object with any property with a value of 6, then you must use for..in unless you pass the names to check.另一方面，如果您确实的确想使用..in并希望找到具有值为6的任何属性的对象，那么除非您通过名称进行检查，否则必须使用for..in。eg例如

function getByValue4(arr, value) {var o;for (var i=0, iLen=arr.length; i<iLen; i++) {o = arr[i];for (var p in o) {if (o.hasOwnProperty(p) && o[p] == value) {return o;}}}}

#5楼

It looks like in the ECMAScript 6 proposal there are theArraymethodsfind()andfindIndex().看起来在ECMAScript 6提案中似乎有Array方法find()和findIndex()。MDN also offers polyfills which you can include to get the functionality of these across all browsers.MDN还提供了polyfill，您可以将其包括在内以在所有浏览器中获得其功能。

find():find()：

function isPrime(element, index, array) {var start = 2;while (start <= Math.sqrt(element)) {if (element % start++ < 1) return false;}return (element > 1);}console.log( [4, 6, 8, 12].find(isPrime) ); // undefined, not foundconsole.log( [4, 5, 8, 12].find(isPrime) ); // 5

findIndex():findIndex()：

function isPrime(element, index, array) {var start = 2;while (start <= Math.sqrt(element)) {if (element % start++ < 1) return false;}return (element > 1);}console.log( [4, 6, 8, 12].findIndex(isPrime) ); // -1, not foundconsole.log( [4, 6, 7, 12].findIndex(isPrime) ); // 2

#6楼

var jsObjects = [{a: 1, b: 2}, {a: 3, b: 4}, {a: 5, b: 6}, {a: 7, b: 8}];

to access the third object, use:jsObjects[2];要访问第三个对象，请使用：jsObjects[2];

to access the third object b value, use:jsObjects[2].b;要访问第三个对象b值，请使用：jsObjects[2].b;