Method _handleKeydown

src/cdk/listbox/listbox.ts:717–815

Called when the user presses keydown on the listbox.

(event: KeyboardEvent)

  /** Called when the user presses keydown on the listbox. */
  protected _handleKeydown(event: KeyboardEvent) {
    if (this.disabled) {
      return;
    }

    const {keyCode} = event;
    const previousActiveIndex = this.listKeyManager.activeItemIndex;
    const ctrlKeys = ['ctrlKey', 'metaKey'] as const;

    if (this.multiple && keyCode === A && hasModifierKey(event, ...ctrlKeys)) {
      // Toggle all options off if they're all selected, otherwise toggle them all on.
      this.triggerRange(
        null,
        0,
        this.options.length - 1,
        this.options.length !== this.value.length,
      );
      event.preventDefault();
      return;
    }

    if (
      this.multiple &&
      (keyCode === SPACE || keyCode === ENTER) &&
      hasModifierKey(event, 'shiftKey')
    ) {
      if (this.listKeyManager.activeItem && this.listKeyManager.activeItemIndex != null) {
        this.triggerRange(
          this.listKeyManager.activeItem,
          this._getLastTriggeredIndex() ?? this.listKeyManager.activeItemIndex,
          this.listKeyManager.activeItemIndex,
          !this.listKeyManager.activeItem.isSelected(),
        );
      }
      event.preventDefault();
      return;
    }

    if (
      this.multiple &&
      keyCode === HOME &&
      hasModifierKey(event, ...ctrlKeys) &&
      hasModifierKey(event, 'shiftKey')
    ) {
      const trigger = this.listKeyManager.activeItem;
      if (trigger) {
        const from = this.listKeyManager.activeItemIndex!;
        this.listKeyManager.setFirstItemActive();
        this.triggerRange(
          trigger,
          from,
          this.listKeyManager.activeItemIndex!,
          !trigger.isSelected(),
        );
      }
      event.preventDefault();
      return;
    }