js Set對象

1、將數組轉換成Set對象

let arr1 = new Set([1,2,3,4])
console.log(arr1)  //{1,2,3,4}

2、數組去重

let arr2 = new Set([1,1,2,3,4])
let arr3 = [...arr2]
console.log(arr2, arr3) // {1,2,3,4} [1,2,3,4]

3、Set.prototype.has(value)判斷該值是否存在於Set對象中，返回布爾值

let arr4 = new Set([1,2,3,4])
console.log(arr4.has(1)) // true

結合filter()方法，返回值為true的集合

let arr = [{id:1, name: 'aaa'}, {id: 2, name: 'bbb'}, {id:3, name: 'cccc'}, {id:4, name: 'dddd'}]
let arr1 = [1,2]
let newarr = arr.filter((item)=>{
    return new Set(arr1).has(item.id)
})
console.log(newarr)
//  [{id:1, name: 'aaa'}, {id:2, name: 'bbb'}]