js 集合的交集、补集、差集、去重

///集合取交集  Array.intersect = function () {      var result = new Array();      var obj = {};      for (var i = 0; i < arguments.length; i++) {          for (var j = 0; j < arguments[i].length; j++) {              var str = arguments[i][j];              if (!obj[str]) {                  obj[str] = 1;              }              else {                  obj[str]++;                  if (obj[str] == arguments.length)                  {                      result.push(str);                  }              }         }     }    return result;  }  //集合去掉重复  Array.prototype.uniquelize = function () {      var tmp = {},          ret = [];      for (var i = 0, j = this.length; i < j; i++) {          if (!tmp[this[i]]) {              tmp[this[i]] = 1;              ret.push(this[i]);          }      }      return ret;  }  //并集  Array.union = function () {      var arr = new Array();      var obj = {};      for (var i = 0; i < arguments.length; i++) {          for (var j = 0; j < arguments[i].length; j++)          {              var str=arguments[i][j];              if (!obj[str])              {                  obj[str] = 1;                  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 = 0; i < arr.length; i++) {          obj[arr[i]] = 1;      }      for (var j = 0; j < this.length; j++) {          if (!obj[this[j]])          {              obj[this[j]] = 1;              result.push(this[j]);          }      }      return result;  };  console.log(Array.intersect(["1", "2", "3"], ["2", "3", "4", "5", "6"]));//[2,3]  console.log([1, 2, 3, 2, 3, 4, 5, 6].uniquelize());//[1,2,3,4,5,6]  console.log(Array.union(["1", "2", "3"], ["2", "3", "4", "5", "6"], ["5", "6", "7", "8", "9"]))  console.log(["2", "3", "4", "5", "6"].minus(["1", "2", "3"]));