数组去重

分类

1. 非对象数组去重
2. 对象数组去重

分类一 --- 非对象数组去重

方法一： set（es6常用）

let arr = [2,3,4,5,5]
let newArr = [...new Set(arr)] // [2,3,4,5]

方法二：reduce

let arr = [2,3,4,4]
let newArr = arr.reduce((prev, item) => {
    !prev.includes(item) && prev.push(item) // 若prev中不存在当前item，则push
    return prev
}, []) // [2,3,4]

方法三：对象key的唯一性

let arr = [2,3,3,4]
let obj = {}
arr.forEach(item => {
    obj[item] = item
})
let newArr = Object.vlaues(obj) // [2,3,4]

分类二 --- 对象数组去重

方法一：对象key的唯一性

let arr = [{id: 1, name: 'a'}, {id: 2, name: 'b'}, {id: 1, name: 'a'}]
let obj = {}
let newArr = []
arr.forEach(item => {
    if(!obj[item.id]) {
        newArr.push(item)
        obj[item.id] = true
    }
}) // [{id: 1, name: 'a'}, {id: 2, name: 'b'}]

方法二：reduce

let arr = [{id: 1, name: 'a'}, {id: 2, name: 'b'}, {id: 1, name: 'a'}]
let obj = {}
arr.reduce((prev, cur) => {
    obj[cur.id] ? '' : obj[cur.id] = true && prev.push(cur)
    return prev
}, []) // [{id: 1, name: 'a'}, {id: 2, name: 'b'}]