code: function uniqueArrayHelper (val) {
          var h = {};
  
          for (var i = 0, l = val.length; i < l; i++) {
              var key = JSON.stringify(val[i]);
              if (h[key]) {
                  return false;
              }
              h[key] = true;
          }
  
          return true;
      }
docs: Check if array is unique
  @param val
  @return {Boolean}