Function useElement

packages/joint-react/src/hooks/use-element.ts:36–62

(
  selector: (item: Element) => ReturnedElements = (item) => item as unknown as ReturnedElements,
  isEqual: (a: ReturnedElements, b: ReturnedElements) => boolean = util.isEqual
)

 * @returns The selected element based on the current cell id.
 */
export function useElement<Element extends GraphElement, ReturnedElements = Element>(
  selector: (item: Element) => ReturnedElements = (item) => item as unknown as ReturnedElements,
  isEqual: (a: ReturnedElements, b: ReturnedElements) => boolean = util.isEqual
): ReturnedElements {
  const id = useCellId();
  const { subscribe, getElement } = useGraphStore();

  const subscribeForElement = useCallback(
    (subscribeCallback: () => void) => {
      return subscribe((changedIds) => {
        if (changedIds?.has(id)) {
          subscribeCallback();
        }
      });
    },
    [id, subscribe]
  );

  const element = useSyncExternalStoreWithSelector(
    subscribeForElement,
    () => getElement<Element>(id),
    () => getElement<Element>(id),
    selector,
    isEqual
  );
  return element;
}