Hi everybody,

Here is a new puzzle. We have a mover type of the control that also allows to re-sort items (e.g. move up or down). Here is the code for up/down movement:

$scope.moveUp = function (smItems) {
                    if (smItems != 'undefined' && smItems.length > 0) {
                        smItems.forEach(function (item) {
                            var sortOrder = $scope.assignedItems.indexOf(item);
                            $scope.assignedItems.move_element(sortOrder, -1);
                        });
                        if (!$scope.keepPristine)
                            $scope.form.$setDirty();
                    };
                };

                $scope.moveDown = function (smItems) {
                    if (smItems != 'undefined' && smItems.length > 0) {
                        smItems.forEach(function (item) {
                            var sortOrder = $scope.assignedItems.indexOf(item);
                            $scope.assignedItems.move_element(sortOrder, 1);
                        });
                        if (!$scope.keepPristine)
                            $scope.form.$setDirty();
                    };
                };

The directive itself is taken from somewhere, I think. Here is the method for moving elements:

 Array.prototype.move_element = function (index, delta) {

            // This method moves an element within the array
            // index = the array item you want to move
            // delta = the direction and number of spaces to move the item.
            //
            // For example:
            // move_element(myarray, 5, -1); // move up one space
            // move_element(myarray, 2, 1); // move down one space
            //
            // Returns true for success, false for error.

            var index2, temp_item;

            // Make sure the index is within the array bounds
            if (index < 0 || index >= this.length) {
                return false;
            }

            // Make sure the target index is within the array bounds
            index2 = index + delta;
            if (index2 < 0 || index2 >= this.length || index2 == index) {
                return false;
            }

            // Move the elements in the array
            temp_item = this[index2];
            this[index2] = this[index];
            this[index] = temp_item;

            return true;
        }

So, my colleagues who are testing our application noticed the following problem (which I can reproduce). We can move items up OK (it seems), but if two items are selected with no item in between them, then we can not move them down. If I select, say, 3rd and 5th item and have more items below, I can move my items down OK (both are moved down).

Do you see what is a bug in the logic here?

Thanks in advance.