// js数组去重
	Array.prototype.fun1 = function(){
	    var arr = this,
	        result = [],
	        i,
	        len = arr.length;
	    for(i = 0;i<len;i++){
	        if(!(arr[i] in result)){
	            result.push(arr[i]);
	        }
	    }
	    return result;
	};
	Array.prototype.fun2 = function(){
	    var arr = this,
	        i,
	        j,
	        len = arr.length;
	    for(i = 0;i<len;i++){
	        for(j = i + 1;j<len;j++){
	            if(arr[i] === arr[j]){
	                arr.splice(j, 1);
	                len --;
	                j --;
	            }
	        }
	    }
	    return arr;
	};
	Array.prototype.fun3 = function(){
	    var arr = this,
	        i,
	        obj = {},
	        result = [],
	        len = arr.length;
	    for(i = 0;i<len;i++){
	        if(!obj[arr[i]]){
	            result.push(arr[i]);
	            obj[arr[i]] = 1;
	        }
	    }
	    return result;
	};
	Array.prototype.fun4 = function(){
	    //数组递归去重
	};
	Array.prototype.fun5 = function(){
	    // [...new Set()]
	};
	Array.prototype.fun6 = function(){
	    // map, filter
	    var arr = this,
	        obj = {},
	        result = [];
	        result = arr.filter((v, k)=>{
	

	        });
	    return result;
	    // arr.map(function(v, k){
	    // });
	    // return arr;
	};
	var arr1 = [1,2,3,2];
	arr1.fun1();