Method _handleUp

packages/base/src/delegate/ItemNavigation.ts:196–215

()

	}

	_handleUp() {
		const itemsLength = this._getItems().length;
		if (this._currentIndex - this._rowSize >= 0) { // no border reached, just decrease the index by a row
			this._currentIndex -= this._rowSize;
			return;
		}

		if (this._behavior === ItemNavigationBehavior.Cyclic) { // if cyclic, go to the **last** item in the **previous** column
			const firstItemInThisColumnIndex = this._currentIndex % this._rowSize;
			const firstItemInPreviousColumnIndex = firstItemInThisColumnIndex === 0 ? this._rowSize - 1 : firstItemInThisColumnIndex - 1; // find the first item in the previous column (if the current column is the first column -> move to the last column)
			const rows = Math.ceil(itemsLength / this._rowSize); // how many rows there are (even if incomplete, f.e. for 14 items and _rowSize=4 -> 4 rows total, although only 2 items on the last row)
			let lastItemInPreviousColumnIndex = firstItemInPreviousColumnIndex + (rows - 1) * this._rowSize; // multiply rows by columns, and add the column's first item's index
			if (lastItemInPreviousColumnIndex > itemsLength - 1) { // for incomplete rows, use the previous row's last item, as for them the last item is missing
				lastItemInPreviousColumnIndex -= this._rowSize;
			}
			this._currentIndex = lastItemInPreviousColumnIndex;
		} else { // not cyclic, so just go to the first item
			this._currentIndex = 0;
		}
	}

	_handleDown() {
		const itemsLength = this._getItems().length;