Function createWorkInProgress

lib/assets/react-source/development/react.js:27388–27480

(current, pendingProps)

	} // This is used to create an alternate fiber to do work on.

	function createWorkInProgress(current, pendingProps) {
	  var workInProgress = current.alternate;

	  if (workInProgress === null) {
	    // We use a double buffering pooling technique because we know that we'll
	    // only ever need at most two versions of a tree. We pool the "other" unused
	    // node that we're free to reuse. This is lazily created to avoid allocating
	    // extra objects for things that are never updated. It also allow us to
	    // reclaim the extra memory if needed.
	    workInProgress = createFiber(current.tag, pendingProps, current.key, current.mode);
	    workInProgress.elementType = current.elementType;
	    workInProgress.type = current.type;
	    workInProgress.stateNode = current.stateNode;

	    {
	      // DEV-only fields
	      {
	        workInProgress._debugID = current._debugID;
	      }

	      workInProgress._debugSource = current._debugSource;
	      workInProgress._debugOwner = current._debugOwner;
	      workInProgress._debugHookTypes = current._debugHookTypes;
	    }

	    workInProgress.alternate = current;
	    current.alternate = workInProgress;
	  } else {
	    workInProgress.pendingProps = pendingProps; // We already have an alternate.
	    // Reset the effect tag.

	    workInProgress.effectTag = NoEffect; // The effect list is no longer valid.

	    workInProgress.nextEffect = null;
	    workInProgress.firstEffect = null;
	    workInProgress.lastEffect = null;

	    {
	      // We intentionally reset, rather than copy, actualDuration & actualStartTime.
	      // This prevents time from endlessly accumulating in new commits.
	      // This has the downside of resetting values for different priority renders,
	      // But works for yielding (the common case) and should support resuming.
	      workInProgress.actualDuration = 0;
	      workInProgress.actualStartTime = -1;
	    }
	  }

	  workInProgress.childExpirationTime = current.childExpirationTime;
	  workInProgress.expirationTime = current.expirationTime;
	  workInProgress.child = current.child;
	  workInProgress.memoizedProps = current.memoizedProps;
	  workInProgress.memoizedState = current.memoizedState;
	  workInProgress.updateQueue = current.updateQueue; // Clone the dependencies object. This is mutated during the render phase, so
	  // it cannot be shared with the current fiber.

	  var currentDependencies = current.dependencies;
	  workInProgress.dependencies = currentDependencies === null ? null : {
	    expirationTime: currentDependencies.expirationTime,