四种数组去重

1.es3函数

//判断一个元素是否存在于某个数组内

function exist(element,array) {        /*array.forEach(function (curr) {            if (curr === element){                return true;            }        })        return false;*/        for (var i = 0;i < array.length;i++) {            if (array[i] === element) {                return true;            }        }        return false;    }    var aki = [];    var ramai = [1,"momo","nagi",1,"ohana","moegumi","suki","omae","momo"];//aki空数组中不存在的就往里面添加，返回的新数组就是需要的去重的数组    function del(arr) {        arr.forEach((curr,index) => {            if (index == 0) {                aki.push(curr);            } else if (!exist(curr,aki)){                aki.push(curr);            }        })        return aki;    }    del(ramai);    console.log(aki)

2.filter瞎几把用

let haha = [1,2,32,14,15,"ww",435,32,2,7,"ww",8];        let strArr = [];        let ret = haha.filter((item) => {            let str = (typeof item) + item;            //console.log(str)            if(!strArr.includes(str)) {                strArr.push(str);                return true;            }            })        console.log(ret)        console.log(strArr) //(9) ["number1", "number2", "number32", "number14", "number15", "stringww", "number435", "number7", "number8"]

filter只关注你给我返回true还是false，true就往ret里加

3.ES5 

var oo = [1,2,3,1,'a',1,'a'].filter(function(ele,index,array){            return index===array.indexOf(ele)        })        console.log(oo)

4.ES6

var haha = [...new Set([1,2,3,1,'a',1,'a'])]        console.log(haha)