Function recursivelyFlushAsyncActWork

packages/react/src/ReactAct.js:271–308

(
  returnValue: T,
  resolve: T => mixed,
  reject: mixed => mixed,
)

}

function recursivelyFlushAsyncActWork<T>(
  returnValue: T,
  resolve: T => mixed,
  reject: mixed => mixed,
) {
  if (__DEV__) {
    // Check if any tasks were scheduled asynchronously.
    const queue = ReactSharedInternals.actQueue;
    if (queue !== null) {
      if (queue.length !== 0) {
        // Async tasks were scheduled, mostly likely in a microtask.
        // Keep flushing until there are no more.
        try {
          flushActQueue(queue);
          // The work we just performed may have schedule additional async
          // tasks. Wait a macrotask and check again.
          queueMacrotask(() =>
            recursivelyFlushAsyncActWork(returnValue, resolve, reject),
          );
          return;
        } catch (error) {
          // Leave remaining tasks on the queue if something throws.
          ReactSharedInternals.thrownErrors.push(error);
        }
      } else {
        // The queue is empty. We can finish.
        ReactSharedInternals.actQueue = null;
      }
    }
    if (ReactSharedInternals.thrownErrors.length > 0) {
      const thrownError = aggregateErrors(ReactSharedInternals.thrownErrors);
      ReactSharedInternals.thrownErrors.length = 0;
      reject(thrownError);
    } else {
      resolve(returnValue);
    }
  }
}

let isFlushing = false;
function flushActQueue(queue: Array<RendererTask>) {