mountClassInstance() — react Function Reference

Source Code

packages/react-server/src/ReactFizzClassComponent.js lines 626–703

export function mountClassInstance(
  instance: any,
  ctor: any,
  newProps: any,
  maskedLegacyContext: any,
): void {
  if (__DEV__) {
    checkClassInstance(instance, ctor, newProps);
  }

  const initialState = instance.state !== undefined ? instance.state : null;

  instance.updater = classComponentUpdater;
  instance.props = newProps;
  instance.state = initialState;
  // We don't bother initializing the refs object on the server, since we're not going to resolve them anyway.

  // The internal instance will be used to manage updates that happen during this mount.
  const internalInstance: InternalInstance = {
    queue: [],
    replace: false,
  };
  setInstance(instance, internalInstance);

  const contextType = ctor.contextType;
  if (typeof contextType === 'object' && contextType !== null) {
    instance.context = readContext(contextType);
  } else if (disableLegacyContext) {
    instance.context = emptyContextObject;
  } else {
    instance.context = maskedLegacyContext;
  }

  if (__DEV__) {
    if (instance.state === newProps) {
      const componentName = getComponentNameFromType(ctor) || 'Component';
      if (!didWarnAboutDirectlyAssigningPropsToState.has(componentName)) {
        didWarnAboutDirectlyAssigningPropsToState.add(componentName);
        console.error(
          '%s: It is not recommended to assign props directly to state ' +
            "because updates to props won't be reflected in state. " +
            'In most cases, it is better to use props directly.',
          componentName,
        );
      }
    }
  }

  const getDerivedStateFromProps = ctor.getDerivedStateFromProps;
  if (typeof getDerivedStateFromProps === 'function') {
    instance.state = applyDerivedStateFromProps(
      instance,
      ctor,
      getDerivedStateFromProps,
      initialState,
      newProps,
    );
  }

  // In order to support react-lifecycles-compat polyfilled components,
  // Unsafe lifecycles should not be invoked for components using the new APIs.
  if (
    typeof ctor.getDerivedStateFromProps !== 'function' &&
    typeof instance.getSnapshotBeforeUpdate !== 'function' &&
    (typeof instance.UNSAFE_componentWillMount === 'function' ||
      typeof instance.componentWillMount === 'function')
  ) {
    callComponentWillMount(ctor, instance);
    // If we had additional state updates during this life-cycle, let's
    // process them now.
    processUpdateQueue(
      internalInstance,
      instance,
      newProps,
      maskedLegacyContext,
    );
  }
}