js数组去重（多种方法）

 1 // js数组去重
 2 Array.prototype.fun1 = function(){
 3     var arr = this,
 4         result = [],
 5         i,
 6         len = arr.length;
 7     for(i = 0;i<len;i++){
 8         if(!(arr[i] in result)){
 9             result.push(arr[i]);
10         }
11     }
12     return result;
13 };
14 Array.prototype.fun2 = function(){
15     var arr = this,
16         i,
17         j,
18         len = arr.length;
19     for(i = 0;i<len;i++){
20         for(j = i + 1;j<len;j++){
21             if(arr[i] === arr[j]){
22                 arr.splice(j, 1);
23                 len --;
24                 j --;
25             }
26         }
27     }
28     return arr;
29 };
30 Array.prototype.fun3 = function(){
31     var arr = this,
32         i,
33         obj = {},
34         result = [],
35         len = arr.length;
36     for(i = 0;i<len;i++){
37         if(!obj[arr[i]]){
38             result.push(arr[i]);
39             obj[arr[i]] = 1;
40         }
41     }
42     return result;
43 };
44 Array.prototype.fun4 = function(){
45     //数组递归去重
46 };
47 Array.prototype.fun5 = function(){
48     // [...new Set()]
49 };
50 Array.prototype.fun6 = function(){
51     // map, filter
52     var arr = this,
53         obj = {},
54         result = [];
55         result = arr.filter((v, k)=>{
56 
57         });
58     return result;
59     // arr.map(function(v, k){
60     // });
61     // return arr;
62 };
63 var arr1 = [1,2,3,2];
64 arr1.fun1();