判断一个对象数组是否包含JavaScript中另一个数组的任何对象

Question

给定以下两个数组对象:

let origArr = [ { value: 2, label: 'Dog' }, 
{ value: 4, label: 'Cat' },
{ value: 16, label: 'Horse' } 
]
let newArr = [
{ value: 2, label: 'Dog' },
{ value: 3, label: 'Bird' },
{ value: 0, label: 'Fish' }
]

返回仅包含origArr和newArr之间的差值的新数组的最佳方法是什么，即origArr元素不在newArr中?

在上面的例子中，我在寻找一个名为diffArr = [4,16]

的新数组请注意:origArr和newArr中的所有value值都是唯一的

不确定是否有ES2016的意思吗?

Answer 1

您可以使用filter和some来完成这项工作。

let origArr = [ { value: 2, label: 'Dog' }, 
{ value: 4, label: 'Cat' },
{ value: 16, label: 'Horse' } 
]
let newArr = [
{ value: 2, label: 'Dog' },
{ value: 3, label: 'Bird' },
{ value: 0, label: 'Fish' }
]
const res = origArr.filter(x => !newArr.some(y => y.value === x.value));
console.log(res); // assuming you want the entire filtered objects
const justValues = res.map(x => x.value); // if you want just the filtered values
console.log(justValues)

some - https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/some

过滤器- https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

Answer 2

您可以使用Set和array#map从newArr中获得所有唯一值，然后过滤集合中不存在的值并获得所有值。

const origArr = [ { value: 2, label: 'Dog' }, { value: 4, label: 'Cat' }, { value: 16, label: 'Horse' } ],
newArr = [ { value: 2, label: 'Dog' }, { value: 3, label: 'Bird' }, { value: 0, label: 'Fish' } ],
unique = new Set(newArr.map(o => o.value)),
difference = origArr
.filter(({value}) => !unique.has(value))
.map(o => o.value);
console.log(difference);