didact-fiber.js

function performUnitOfWork(wipFiber) {
  beginWork(wipFiber);
  if (wipFiber.child) {
    return wipFiber.child;
  }

  // No child, we call completeWork until we find a sibling
  let uow = wipFiber;
  while (uow) {
    completeWork(uow);
    if (uow.sibling) {
      // Sibling needs to beginWork
      return uow.sibling;
    }
    uow = uow.parent;
  }
}