React 钩子

一、作用

二、获取类型缓存

备注

• ReactSharedInternals() 由 ReactSharedInternals 实现

export function getCacheForType<T>(resourceType: () => T): T {
  const dispatcher = ReactSharedInternals.A;
  if (!dispatcher) {
    // If there is no dispatcher, then we treat this as not being cached.
    // 如果没有调度器，那么我们将其视为未缓存。
    return resourceType();
  }
  return dispatcher.getCacheForType(resourceType);
}

三、useContext()

export function useContext<T>(Context: ReactContext<T>): T {
  const dispatcher = resolveDispatcher();
  if (__DEV__) {
    if (Context.$$typeof === REACT_CONSUMER_TYPE) {
      console.error(
        'Calling useContext(Context.Consumer) is not supported and will cause bugs. ' +
          'Did you mean to call useContext(Context) instead?',
      );
    }
  }
  return dispatcher.useContext(Context);
}

四、useState()

export function useState<S>(
  initialState: (() => S) | S,
): [S, Dispatch<BasicStateAction<S>>] {
  const dispatcher = resolveDispatcher();
  return dispatcher.useState(initialState);
}

五、useReducer()

export function useReducer<S, I, A>(
  reducer: (S, A) => S,
  initialArg: I,
  init?: I => S,
): [S, Dispatch<A>] {
  const dispatcher = resolveDispatcher();
  return dispatcher.useReducer(reducer, initialArg, init);
}

六、useRef()

export function useRef<T>(initialValue: T): { current: T } {
  const dispatcher = resolveDispatcher();
  return dispatcher.useRef(initialValue);
}

七、useEffect()

export function useEffect(
  create: () => (() => void) | void,
  deps: Array<mixed> | void | null,
): void {
  if (__DEV__) {
    if (create == null) {
      console.warn(
        'React Hook useEffect requires an effect callback. Did you forget to pass a callback to the hook?',
      );
    }
  }

  const dispatcher = resolveDispatcher();
  return dispatcher.useEffect(create, deps);
}

八、useInsertionEffect()

export function useInsertionEffect(
  create: () => (() => void) | void,
  deps: Array<mixed> | void | null,
): void {
  if (__DEV__) {
    if (create == null) {
      console.warn(
        'React Hook useInsertionEffect requires an effect callback. Did you forget to pass a callback to the hook?',
      );
    }
  }

  const dispatcher = resolveDispatcher();
  return dispatcher.useInsertionEffect(create, deps);
}

九、useLayoutEffect()

export function useLayoutEffect(
  create: () => (() => void) | void,
  deps: Array<mixed> | void | null,
): void {
  if (__DEV__) {
    if (create == null) {
      console.warn(
        'React Hook useLayoutEffect requires an effect callback. Did you forget to pass a callback to the hook?',
      );
    }
  }

  const dispatcher = resolveDispatcher();
  return dispatcher.useLayoutEffect(create, deps);
}

十、useCallback()

export function useCallback<T>(
  callback: T,
  deps: Array<mixed> | void | null,
): T {
  const dispatcher = resolveDispatcher();
  return dispatcher.useCallback(callback, deps);
}

十一、useMemo()

export function useMemo<T>(
  create: () => T,
  deps: Array<mixed> | void | null,
): T {
  const dispatcher = resolveDispatcher();
  return dispatcher.useMemo(create, deps);
}

十二、useImperativeHandle()

export function useImperativeHandle<T>(
  ref: { current: T | null } | ((inst: T | null) => mixed) | null | void,
  create: () => T,
  deps: Array<mixed> | void | null,
): void {
  const dispatcher = resolveDispatcher();
  return dispatcher.useImperativeHandle(ref, create, deps);
}

十三、useDebugValue()

export function useDebugValue<T>(
  value: T,
  formatterFn: ?((value: T) => mixed),
): void {
  if (__DEV__) {
    const dispatcher = resolveDispatcher();
    return dispatcher.useDebugValue(value, formatterFn);
  }
}

十四、useTransition()

export function useTransition(): [
  boolean,
  (callback: () => void, options?: StartTransitionOptions) => void,
] {
  const dispatcher = resolveDispatcher();
  return dispatcher.useTransition();
}

十五、useDeferredValue()

export function useDeferredValue<T>(value: T, initialValue?: T): T {
  const dispatcher = resolveDispatcher();
  return dispatcher.useDeferredValue(value, initialValue);
}

十六、useId()

export function useId(): string {
  const dispatcher = resolveDispatcher();
  return dispatcher.useId();
}

十七、useSyncExternalStore()

export function useSyncExternalStore<T>(
  subscribe: (() => void) => () => void,
  getSnapshot: () => T,
  getServerSnapshot?: () => T,
): T {
  const dispatcher = resolveDispatcher();
  return dispatcher.useSyncExternalStore(
    subscribe,
    getSnapshot,
    getServerSnapshot,
  );
}

十八、useCacheRefresh()

export function useCacheRefresh(): <T>(?() => T, ?T) => void {
  const dispatcher = resolveDispatcher();
  return dispatcher.useCacheRefresh();
}

十九、use()

export function use<T>(usable: Usable<T>): T {
  const dispatcher = resolveDispatcher();
  return dispatcher.use(usable);
}

二十、useMemoCache)

export function useMemoCache(size: number): Array<mixed> {
  const dispatcher = resolveDispatcher();
  return dispatcher.useMemoCache(size);
}

廿一、useEffectEvent()

// export function useEffectEvent<Args, F: (...Array<Args>) => mixed>(
export function useEffectEvent<Args, F extends (...arr: Array<Args>) => mixed>(
  callback: F,
): F {
  const dispatcher = resolveDispatcher();

  return dispatcher.useEffectEvent(callback);
}

廿二、useOptimistic()

export function useOptimistic<S, A>(
  passthrough: S,
  reducer: ?((S, A) => S),
): [S, (A) => void] {
  const dispatcher = resolveDispatcher();
  return dispatcher.useOptimistic(passthrough, reducer);
}

廿三、useActionState()

export function useActionState<S, P>(
  // action: (Awaited<S>, P) => S,
  action: (awaited: Awaited<S>, p: P) => S,
  initialState: Awaited<S>,
  permalink?: string,
): [Awaited<S>, (P) => void, boolean] {
  const dispatcher = resolveDispatcher();
  return dispatcher.useActionState(action, initialState, permalink);
}

廿四、工具

1. 解析调度器

function resolveDispatcher() {
  const dispatcher = ReactSharedInternals.H;
  if (__DEV__) {
    if (dispatcher === null) {
      console.error(
        'Invalid hook call. Hooks can only be called inside of the body of a function component. This could happen for' +
          ' one of the following reasons:\n' +
          '1. You might have mismatching versions of React and the renderer (such as React DOM)\n' +
          '2. You might be breaking the Rules of Hooks\n' +
          '3. You might have more than one copy of React in the same app\n' +
          'See https://react.dev/link/invalid-hook-call for tips about how to debug and fix this problem.',
      );
    }
  }
  // Will result in a null access error if accessed outside render phase. We
  // intentionally don't throw our own error because this is in a hot path.
  // Also helps ensure this is inlined.
  //
  // 如果在渲染阶段之外访问，将导致 null 访问错误。我们故意不抛出自己的错误，因为这是热路径的
  // 一部分。同时有助于确保此代码被内联。
  return dispatcher as any as Dispatcher;
}