Function performUnitOfWork

code/event-handlers/public/app.js:12546–12579

(workInProgress)

  }

  function performUnitOfWork(workInProgress) {
    // The current, flushed, state of this fiber is the alternate.
    // Ideally nothing should rely on this, but relying on it here
    // means that we don't need an additional field on the work in
    // progress.
    var current = workInProgress.alternate;

    // See if beginning this work spawns more work.
    startWorkTimer(workInProgress);
    {
      ReactDebugCurrentFiber.setCurrentFiber(workInProgress);
    }

    if (true && replayFailedUnitOfWorkWithInvokeGuardedCallback) {
      stashedWorkInProgressProperties = _assign({}, workInProgress);
    }
    var next = beginWork(current, workInProgress, nextRenderExpirationTime);

    {
      ReactDebugCurrentFiber.resetCurrentFiber();
    }
    if (true && ReactFiberInstrumentation_1.debugTool) {
      ReactFiberInstrumentation_1.debugTool.onBeginWork(workInProgress);
    }

    if (next === null) {
      // If this doesn't spawn new work, complete the current work.
      next = completeUnitOfWork(workInProgress);
    }

    ReactCurrentOwner.current = null;

    return next;
  }

  function workLoop(isAsync) {
    if (!isAsync) {