本文共 3569 字，大约阅读时间需要 11 分钟。

本文翻译自：

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 property b for example without a for...in loop? 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：

#2楼

Filter array 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 请参阅的

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)

Find the value of the first element/object in the array, otherwise undefined is 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 请参阅的

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 whose b property is 6 ? 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

.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

#5楼

It looks like in the ECMAScript 6 proposal there are the Array methods find() and findIndex() . 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。

: ：

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

: ：

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];

转载地址：http://cjcnb.baihongyu.com/