给出以下数组

var arr1 = new Array('1','2','3','3','5','4','5','6','5','5','88');

实现对数组的去重

1、 双重for循环去重

Array.prototype.Duplicate = function() {    let arr = this;    for(let i = 0; i < arr.length-1; i++) {    　　for (let j = i+1; j < arr.length; j++) {        　　if (arr[i] == arr[j]) {            　　arr.splice(j, 1);            　　j--;  // 删除元素之后，需要将数组的长度也减1，否则无法去除掉后面相同的值.        　　};    　　};    };    return arr;}

2、 利用递归调用去重

Array.prototype.Duplicate = function() {    let arr = this;    arr.sort();    function loop(index) {        if (index > 1) {            if (arr[index] == arr[index-1]) {                arr.splice(index, 1);            };            loop(index-1);        };    };    loop(arr.length-1);    return arr;}

3、 利用对象去重

Array.prototype.Duplicate = function() {    let arr = this;    let obj = {}    let arr2 = []    for (let i = 0; i < arr.length; i++) {        if (!obj[arr[i]]) {            obj[arr[i]] = true;            arr2.push(arr[i]);        }    };    return arr2;}

4、 利用indexOf

Array.prototype.Duplicate = function() {    let arr = this;    let arr2 = []    for (let i = 0; i < arr.length; i++) {        if (arr2.indexOf(arr[i]) == -1) {            arr2.push(arr[i]);        }    };    return arr2;}

5、 利用es6 includes方法判断

Array.prototype.Duplicate = function() {    let arr = this;    let arr2 = [];    for (let i = 0; i < arr.length; i++) {        if (!arr2.includes(arr[i])) {            arr2.push(arr[i]);        }    }    return arr2}

console.log(arr1.Duplicate().toString());

// 1,2,3,5,4,6,88