js数组去重的11种方法

var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5,5,5,5];
    console.log(arr);    //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5, 5, 5, 5]
    function noRepeat1(arr) {
        for(var i = 0; i < arr.length-1; i++){
            for(var j = i+1; j < arr.length; j++){
                if(arr[i]===arr[j]){
                    arr.splice(j,1);
                    j--;
                }
            }
        }
        return arr;
    }
    var arr2 = noRepeat1(arr);
    console.log(arr2);    //[1, 23, 3, 5, 6, 7, 9, 8]

var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5,5,5];
    console.log(arr);    //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5, 5, 5]
    function noRepeat2(arr) {
        for (var i = 0; i < arr.length; i++) {
            if (arr.indexOf(arr[i]) != i) {
                arr.splice(i,1);//删除数组元素后数组长度减1后面的元素前移
                i--;//数组下标回退
            }
        }
        return arr;
    }
    var newArr = noRepeat2(arr);
    console.log(newArr);    //[1, 23, 3, 5, 6, 7, 9, 8]

var arr = ['apple','banana','pear','apple','orange','orange'];
console.log(arr)    //["apple", "banana", "pear", "apple", "orange", "orange"]
var newArr = arr.filter(function(value,index,self){
    return self.indexOf(value) === index;
});
console.log(newArr);    //["apple", "banana", "pear", "orange"]

var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5,5,5];
    console.log(arr)    //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5, 5, 5]
    function noRepeat4(arr) {
        var ret = [];
        for (var i = 0; i < arr.length; i++) {
            if (arr.indexOf(arr[i]) == i) {
                ret.push(arr[i]);
            }
        }
        return ret;
    }
    var arr2 = noRepeat4(arr);
    console.log(arr2);    //[1, 23, 3, 5, 6, 7, 9, 8]

var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5];
    console.log(arr)    //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5]
    var obj={};
    var newArr=[];
    for(var i=0;i<arr.length;i++){
        if(!obj[arr[i]]){
            obj[arr[i]]=true;
            newArr.push(arr[i]);
        }
    }
    console.log(newArr);    //[1, 23, 3, 5, 6, 7, 9, 8]

var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5];
    console.log(arr);    //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5]
    function noRepeat6(arr){
        var newArr = [];
        for(var i = 0; i < arr.length; i++){
            if(newArr.indexOf(arr[i]) == -1){
                newArr.push(arr[i]);
            }
        }
        return newArr;
    }
    var arr2 = noRepeat6(arr);
    console.log(arr2);    //[1, 23, 3, 5, 6, 7, 9, 8]

var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5];
    console.log(arr);    //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5]
    function noRepeat7(arr) {
        var ret = [],
            end;//临时变量用于对比重复元素
        arr.sort();//将数重新组排序
        end = arr[0];
        ret.push(arr[0]);
        for (var i = 1; i < arr.length; i++) {
            if (arr[i] != end) {//当前元素如果和临时元素不等则将此元素添加到新数组中
                ret.push(arr[i]);
                end = arr[i];
            }
        }
        return ret;
    }
    var arr2 = noRepeat7(arr);
    console.log(arr2);    //[1, 23, 3, 5, 6, 7, 8, 9]

var arr = [1,23,1,1,1,3,23,5,6,7,9,9,8,5];
    console.log(arr);    //[1, 23, 1, 1, 1, 3, 23, 5, 6, 7, 9, 9, 8, 5]
    function noRepeat8(arr) {
        var end;//临时变量用于对比重复元素
        arr.sort();//将数重新组排序
        end = arr[0];
        for (var i = 1; i < arr.length; i++) {
            if (arr[i] == end) {//当前元素如果和临时元素相等则将此元素从数组中删除
                arr.splice(i,1);
                i--;
            }else{
                end = arr[i];
            }
        }
        return arr;
    }
    var arr2 = noRepeat8(arr);
    console.log(arr2);    //[1, 23, 3, 5, 6, 7, 8, 9]

var arr = [1,1,2,2,3,3,4,4,5,5,4,3,1,2,6,6,6,6];
    console.log(arr);    //[1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 4, 3, 1, 2, 6, 6, 6, 6]
    function noRepeat9(arr){
        for (var i = 0; i < arr.length; i++) {
            for (var j = 0; j < arr.length; j++) {
                if (arr[i] == arr[j] && i != j) {//将后面重复的数删掉
                    arr.splice(j, 1);
                }
            }
        }
        return arr;
    }
    var arr2  = noRepeat9(arr);
    console.log(arr2);    //[1, 2, 3, 4, 5, 6]

var arr = [1,1,2,2,3,3,4,4,5,5,4,3,2,1,1,1];
    console.log(arr);    //[1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 4, 3, 2, 1, 1, 1]
    var newArr = [];
    for (var i = 0; i < arr.length; i++) {
        var repArr = [];//接收重复数据后面的下标
        //内层循环找出有重复数据的下标
        for (var j = i + 1; j < arr.length; j++) {
            if (arr[i] == arr[j]) {
                repArr.push(j);//找出后面重复数据的下标
            }
        }
        //console.log(repArr);
        if (repArr.length == 0) {//若重复数组没有值说明其不是重复数据
            newArr.push(arr[i]);
        }
    }
    console.log(newArr);    //[5, 4, 3, 2, 1]

var arr = [1,1,2,2,3,3,4,4,5,5,4,3,2,1,1,1];
    console.log(arr);    //[1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 4, 3, 2, 1, 1, 1]
    function noRepeat11(arr){
        var newArr = [];
        var myset = new Set(arr);//利用了Set结构不能接收重复数据的特点
        for(var val of myset){
            newArr.push(val)
        }
        return newArr;
    }
    var arr2 = noRepeat11(arr)
    console.log(arr2);    //[1, 2, 3, 4, 5]