Function updateSlot

docs/index.js:6463–6511

(returnFiber, oldFiber, newChild, lanes)

    return null;
  }
  function updateSlot(returnFiber, oldFiber, newChild, lanes) {
    var key = null !== oldFiber ? oldFiber.key : null;
    if (
      ("string" === typeof newChild && "" !== newChild) ||
      "number" === typeof newChild ||
      "bigint" === typeof newChild
    )
      return null !== key
        ? null
        : updateTextNode(returnFiber, oldFiber, "" + newChild, lanes);
    if ("object" === typeof newChild && null !== newChild) {
      switch (newChild.$$typeof) {
        case REACT_ELEMENT_TYPE:
          return newChild.key === key
            ? updateElement(returnFiber, oldFiber, newChild, lanes)
            : null;
        case REACT_PORTAL_TYPE:
          return newChild.key === key
            ? updatePortal(returnFiber, oldFiber, newChild, lanes)
            : null;
        case REACT_LAZY_TYPE:
          return (
            (key = newChild._init),
            (newChild = key(newChild._payload)),
            updateSlot(returnFiber, oldFiber, newChild, lanes)
          );
      }
      if (isArrayImpl(newChild) || getIteratorFn(newChild))
        return null !== key
          ? null
          : updateFragment(returnFiber, oldFiber, newChild, lanes, null);
      if ("function" === typeof newChild.then)
        return updateSlot(
          returnFiber,
          oldFiber,
          unwrapThenable(newChild),
          lanes
        );
      if (newChild.$$typeof === REACT_CONTEXT_TYPE)
        return updateSlot(
          returnFiber,
          oldFiber,
          readContextDuringReconciliation(returnFiber, newChild),
          lanes
        );
      throwOnInvalidObjectType(returnFiber, newChild);
    }
    return null;
  }
  function updateFromMap(
    existingChildren,
    returnFiber,