code: function fieldReorder(elem, field, val, pos) {
          try {
              $(exports).triggerHandler('fieldReorder', [elem, field, val, pos]);
          } catch (err) {
              console.error(err);
          }
          _currentOperation.ops.push({
              op: OP_FIELD_REORDER,
              arg: {
                  _id: elem._id,
                  f: field,
                  e: val._id,
                  i: pos
              }
          });
      }
docs: Change order of a value in array field.
  
  @param {Element} elem
  @param {string} field
  @param {?} val
  @param {number} pos Position to be placed