useEffect

初始化

将方法放入 effectList。

function mountEffect(
  create: () => (() => void) | void,
  deps: Array<mixed> | void | null,
): void {
  return mountEffectImpl(
    UpdateEffect | PassiveEffect,
    UnmountPassive | MountPassive,
    create,
    deps,
  );
}

function mountEffectImpl(fiberEffectTag, hookEffectTag, create, deps): void {
  const hook = mountWorkInProgressHook();
  const nextDeps = deps === undefined ? null : deps;
  sideEffectTag |= fiberEffectTag;
  hook.memoizedState = pushEffect(hookEffectTag, create, undefined, nextDeps);
}

更新

对依赖进行潜比较，如果不一样，将方法放入 effectList。

function updateEffect(
  create: () => (() => void) | void,
  deps: Array<mixed> | void | null,
): void {
  return updateEffectImpl(
    UpdateEffect | PassiveEffect,
    UnmountPassive | MountPassive,
    create,
    deps,
  );
}

function updateEffectImpl(fiberEffectTag, hookEffectTag, create, deps): void {
  const hook = updateWorkInProgressHook();
  const nextDeps = deps === undefined ? null : deps;
  let destroy = undefined;

  if (currentHook !== null) {
    const prevEffect = currentHook.memoizedState;
    destroy = prevEffect.destroy;
    if (nextDeps !== null) {
      const prevDeps = prevEffect.deps;
      if (areHookInputsEqual(nextDeps, prevDeps)) {
        pushEffect(NoHookEffect, create, destroy, nextDeps);
        return;
      }
    }
  }

  sideEffectTag |= fiberEffectTag;
  hook.memoizedState = pushEffect(hookEffectTag, create, destroy, nextDeps);
}