js求两个数组的并集

    function mergeArray(arr1, arr2) {                            var arr = [];              for (var i = 0; i < arr1.length; i++) {              arr.push(arr1[i]);              }                  var dup;                  for (var i = 0; i < arr2.length; i++){                  dup = false;                  for (var i = 0; i < arr1.length; i++){                  if (arr2[i] == arr1[i]){                  dup = true;                  break;                  }              }                  if (!dup){                  arr.push(arr2[i]);                  }              }                            return arr;          }