Function useToastRegion

packages/react-aria/src/toast/useToastRegion.ts:46–221

(
  props: AriaToastRegionProps,
  state: ToastState<T>,
  ref: RefObject<HTMLElement | null>
)

 * application.
 */
export function useToastRegion<T>(
  props: AriaToastRegionProps,
  state: ToastState<T>,
  ref: RefObject<HTMLElement | null>
): ToastRegionAria {
  let stringFormatter = useLocalizedStringFormatter(intlMessages, '@react-aria/toast');
  let {landmarkProps} = useLandmark(
    {
      role: 'region',
      'aria-label':
        props['aria-label'] ||
        stringFormatter.format('notifications', {count: state.visibleToasts.length})
    },
    ref
  );

  let isHovered = useRef(false);
  let isFocused = useRef(false);
  let updateTimers = useCallback(() => {
    if (isHovered.current || isFocused.current) {
      state.pauseAll();
    } else {
      state.resumeAll();
    }
  }, [state]);

  let {hoverProps} = useHover({
    onHoverStart: () => {
      isHovered.current = true;
      updateTimers();
    },
    onHoverEnd: () => {
      isHovered.current = false;
      updateTimers();
    }
  });

  // Manage focus within the toast region.
  // If a focused containing toast is removed, move focus to the next toast, or the previous toast if there is no next toast.
  let toasts = useRef<FocusableElement[]>([]);
  let prevVisibleToasts = useRef(state.visibleToasts);
  let focusedToast = useRef<number | null>(null);
  useLayoutEffect(() => {
    // If no toast has focus, then don't do anything.
    if (focusedToast.current === -1 || state.visibleToasts.length === 0 || !ref.current) {
      toasts.current = [];
      prevVisibleToasts.current = state.visibleToasts;
      return;
    }
    toasts.current = [
      ...ref.current.querySelectorAll('[role="alertdialog"]')
    ] as FocusableElement[];
    // If the visible toasts haven't changed, we don't need to do anything.
    if (
      prevVisibleToasts.current.length === state.visibleToasts.length &&
      state.visibleToasts.every((t, i) => t.key === prevVisibleToasts.current[i].key)
    ) {
      prevVisibleToasts.current = state.visibleToasts;