js Array 交集 并集 差集 去重

最劲项目需要用到js数组去重和交集的一些运算，我的数组元素个数可能到达1000以上，网上的实现方式都是2次循环，性能不适合我的需求，1000*1000那循环次数太多了，所以我这里采用对象object来做处理，用空间换时间，code 如下：

        ///集合取交集
        Array.intersect = function () {
            var result = new Array();
            var obj = {};
            for (var i = ; i < arguments.length; i++) {
                for (var j = ; j < arguments[i].length; j++) {
                    var str = arguments[i][j];
                    if (!obj[str]) {
                        obj[str] = ;
                    }
                    else {
                        obj[str]++;
                        if (obj[str] == arguments.length)
                        {
                            result.push(str);
                        }
                    }//end else
                }//end for j
            }//end for i
            return result;
        }

        //集合去掉重复
        Array.prototype.uniquelize = function () {
            var tmp = {},
                ret = [];
            for (var i = , j = this.length; i < j; i++) {
                if (!tmp[this[i]]) {
                    tmp[this[i]] = ;
                    ret.push(this[i]);
                }
            }

            return ret;
        }
        //并集
        Array.union = function () {
            var arr = new Array();
            var obj = {};
            for (var i = ; i < arguments.length; i++) {
                for (var j = ; j < arguments[i].length; j++)
                {
                    var str=arguments[i][j];
                    if (!obj[str])
                    {
                        obj[str] = ;
                        arr.push(str);
                    }
                }//end for j
            }//end for i
            return arr;
        }

        //2个集合的差集 在arr不存在
        Array.prototype.minus = function (arr) {
            var result = new Array();
            var obj = {};
            for (var i = ; i < arr.length; i++) {
                obj[arr[i]] = ;
            }
            for (var j = ; j < this.length; j++) {
                if (!obj[this[j]])
                {
                    obj[this[j]] = ;
                    result.push(this[j]);
                }
            }
            return result;
        };

        console.log(Array.intersect(["", "", ""], ["", "", "", "", ""]));//[2,3]
        console.log([, , , , , , , ].uniquelize());//[1,2,3,4,5,6]
        console.log(Array.union(["", "", ""], ["", "", "", "", ""], ["", "", "", "", ""]))
        console.log(["", "", "", "", ""].minus(["", "", ""]));