updateClassComponent() — react Function Reference

Source Code

packages/react-reconciler/src/ReactFiberBeginWork.js lines 1576–1686

function updateClassComponent(
  current: Fiber | null,
  workInProgress: Fiber,
  Component: any,
  nextProps: any,
  renderLanes: Lanes,
) {
  if (__DEV__) {
    // This is used by DevTools to force a boundary to error.
    switch (shouldError(workInProgress)) {
      case false: {
        const instance = workInProgress.stateNode;
        const ctor = workInProgress.type;
        // TODO This way of resetting the error boundary state is a hack.
        // Is there a better way to do this?
        const tempInstance = new ctor(
          workInProgress.memoizedProps,
          instance.context,
        );
        const state = tempInstance.state;
        instance.updater.enqueueSetState(instance, state, null);
        break;
      }
      case true: {
        workInProgress.flags |= DidCapture;
        workInProgress.flags |= ShouldCapture;
        // eslint-disable-next-line react-internal/prod-error-codes
        const error = new Error('Simulated error coming from DevTools');
        const lane = pickArbitraryLane(renderLanes);
        workInProgress.lanes = mergeLanes(workInProgress.lanes, lane);
        // Schedule the error boundary to re-render using updated state
        const root: FiberRoot | null = getWorkInProgressRoot();
        if (root === null) {
          throw new Error(
            'Expected a work-in-progress root. This is a bug in React. Please file an issue.',
          );
        }
        const update = createClassErrorUpdate(lane);
        initializeClassErrorUpdate(
          update,
          root,
          workInProgress,
          createCapturedValueAtFiber(error, workInProgress),
        );
        enqueueCapturedUpdate(workInProgress, update);
        break;
      }
    }
  }

  // Push context providers early to prevent context stack mismatches.
  // During mounting we don't know the child context yet as the instance doesn't exist.
  // We will invalidate the child context in finishClassComponent() right after rendering.
  let hasContext;
  if (isLegacyContextProvider(Component)) {
    hasContext = true;
    pushLegacyContextProvider(workInProgress);
  } else {
    hasContext = false;
  }
  prepareToReadContext(workInProgress, renderLanes);

  const instance = workInProgress.stateNode;
  let shouldUpdate;
  if (instance === null) {
    resetSuspendedCurrentOnMountInLegacyMode(current, workInProgress);

    // In the initial pass we might need to construct the instance.
    constructClassInstance(workInProgress, Component, nextProps);
    mountClassInstance(workInProgress, Component, nextProps, renderLanes);
    shouldUpdate = true;
  } else if (current === null) {
    // In a resume, we'll already have an instance we can reuse.
    shouldUpdate = resumeMountClassInstance(
      workInProgress,
      Component,
      nextProps,
      renderLanes,
    );
  } else {
    shouldUpdate = updateClassInstance(