Function updateFromMap

docs/index.js:6512–6581

(
    existingChildren,
    returnFiber,
    newIdx,
    newChild,
    lanes
  )

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