假设我有一个包含四个对象的数组:
var jsObjects = [
{a: 1, b: 2},
{a: 3, b: 4},
{a: 5, b: 6},
{a: 7, b: 8}
];
是否有一种方法，我可以通过属性b的值获得第三个对象({a: 5, b: 6})例如，没有a for…在循环?
当前回答
参见本文档Array.prototype.find()
例子:
var inventory = [
{name: 'apples', quantity: 2},
{name: 'bananas', quantity: 0},
{name: 'cherries', quantity: 5}
];
function findCherries(fruit) {
return fruit.name === 'cherries';
}
console.log(inventory.find(findCherries));
// { name: 'cherries', quantity: 5 }
其他回答
你可以像下面这样使用箭头函数:
var demoArray = [
{name: 'apples', quantity: 2},
{name: 'bananas', quantity: 0},
{name: 'cherries', quantity: 5}
];
var result = demoArray.filter( obj => obj.name === 'apples')[0];
console.log(result);
// {name: 'apples', quantity: 2}
看起来在ECMAScript 6提案中有数组方法find()和findIndex()。MDN还提供了可以包含在所有浏览器中获得这些功能的腻子。
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 found
console.log( [4, 5, 8, 12].find(isPrime) ); // 5
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 found
console.log( [4, 6, 7, 12].findIndex(isPrime) ); // 2
使用underscore.js:
var foundObject = _.findWhere(jsObjects, {b: 6});
实现需求的方法:
使用Array.find()方法:
const jsObject = [ {a: 1, b: 2}， {a: 3, b: 4}， {a: 5, b: 6}， {a: 7, b: 8} ]; const filteredResult = jsObject.find((e) => e.b == 6); console.log (filteredResult);
使用Array.filter()方法:
const jsObjects = [ {a: 1, b: 2}， {a: 3, b: 4}， {a: 5, b: 6}， {a: 7, b: 8} ]; const filterObj = jsObjects.filter((e) => e.b == 6); console.log (filterObj [0]);
使用……循环中:
const jsObjects = [ {a: 1, b: 2}， {a: 3, b: 4}， {a: 5, b: 6}， {a: 7, b: 8} ]; for (const i in jsObjects) { 如果(jsObjects[我]。B == 6) { console.log (jsObjects[我]); ｝ ｝
参见本文档Array.prototype.find()
例子:
var inventory = [
{name: 'apples', quantity: 2},
{name: 'bananas', quantity: 0},
{name: 'cherries', quantity: 5}
];
function findCherries(fruit) {
return fruit.name === 'cherries';
}
console.log(inventory.find(findCherries));
// { name: 'cherries', quantity: 5 }
