数组排序去重

1.数组排序

　　升序

        var arr = [1,4,24,21,44,22,24,41,5,7,56,7];
        console.log(arr);//[1, 4, 24, 21, 44, 22, 24, 41, 5, 7, 56, 7]
        var arr2 = [];
        arr.sort(function(x,y){
            return x-y;//升序
        })
        console.log(arr); // [1, 4, 5, 7, 7, 21, 22, 24, 24, 41, 44, 56]

　　降序

     　　arr.sort(function(x,y){
            return y-x;//降序
        })
        console.log(arr);//[56, 44, 41, 24, 24, 22, 21, 7, 7, 5, 4, 1]

2.数组去重（不排序的）

        var arr = [1,4,24,21,44,22,24,41,5,7,56,7];
        console.log(arr);//[1, 4, 24, 21, 44, 22, 24, 41, 5, 7, 56, 7]
        var arr2 = [];
        for(var i = 0;i<arr.length;i++){
            if (arr2.indexOf(arr[i]) == '-1') {
                arr2.push(arr[i]);
            }
        }
        console.log(arr2);//  [1, 4, 24, 21, 44, 22, 41, 5, 7, 56]

　　排序去重（根据具体是升序还是降序排序）

　　

        var arr = [1,4,24,21,44,22,24,41,5,7,56,7];
        console.log(arr);//[1, 4, 24, 21, 44, 22, 24, 41, 5, 7, 56, 7]
        var arr2 = [];
        arr.sort(function(x,y){
            return x-y;//升序
        })
        console.log(arr); // [1, 4, 5, 7, 7, 21, 22, 24, 24, 41, 44, 56]
        for(var i = 0;i<arr.length;i++){
            if (arr2.indexOf(arr[i]) == '-1') {
                arr2.push(arr[i]);
            }
        }
        console.log(arr2);//  [1, 4, 5, 7, 21, 22, 24, 41, 44, 56]