JS合并两个数组，去除重复的部分

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;

}