Function checkShouldComponentUpdate

docs/external/js/react-dom.development.js:12817–12846

(workInProgress, ctor, oldProps, newProps, oldState, newState, nextContext)

  };

  function checkShouldComponentUpdate(workInProgress, ctor, oldProps, newProps, oldState, newState, nextContext) {
    var instance = workInProgress.stateNode;

    if (typeof instance.shouldComponentUpdate === 'function') {
      {
        if ( workInProgress.mode & StrictMode) {
          // Invoke the function an extra time to help detect side-effects.
          instance.shouldComponentUpdate(newProps, newState, nextContext);
        }
      }

      startPhaseTimer(workInProgress, 'shouldComponentUpdate');
      var shouldUpdate = instance.shouldComponentUpdate(newProps, newState, nextContext);
      stopPhaseTimer();

      {
        if (shouldUpdate === undefined) {
          error('%s.shouldComponentUpdate(): Returned undefined instead of a ' + 'boolean value. Make sure to return true or false.', getComponentName(ctor) || 'Component');
        }
      }

      return shouldUpdate;
    }

    if (ctor.prototype && ctor.prototype.isPureReactComponent) {
      return !shallowEqual(oldProps, newProps) || !shallowEqual(oldState, newState);
    }

    return true;
  }

  function checkClassInstance(workInProgress, ctor, newProps) {
    var instance = workInProgress.stateNode;