Function createWorkInProgress

packages/react-reconciler/src/fiber.ts:135–174

(
	current: FiberNode,
	pendingProps: Props
)

}

export const createWorkInProgress = (
	current: FiberNode,
	pendingProps: Props
): FiberNode => {
	let wip = current.alternate;
	if (wip === null) {
		// mount
		wip = new FiberNode(current.tag, pendingProps, current.key);
		wip.stateNode = current.stateNode;

		wip.alternate = current;
		current.alternate = wip;
	} else {
		// update
		wip.pendingProps = pendingProps;
		wip.flags = NoFlags;
		wip.subtreeFlags = NoFlags;
		wip.deletions = null;
	}
	wip.type = current.type;
	wip.updateQueue = current.updateQueue;
	wip.child = current.child;
	wip.memoizedProps = current.memoizedProps;
	wip.memoizedState = current.memoizedState;
	wip.ref = current.ref;

	wip.lanes = current.lanes;
	wip.childLanes = current.childLanes;

	const currentDeps = current.dependencies;
	wip.dependencies =
		currentDeps === null
			? null
			: {
					lanes: currentDeps.lanes,
					firstContext: currentDeps.firstContext
			  };

	return wip;
};

export function createFiberFromElement(element: ReactElementType): FiberNode {
	const { type, key, props, ref } = element;