Function updateSuspenseFallbackChildren

dash/deps/react-dom@18.2.0.js:20494–20557

(current, workInProgress, primaryChildren, fallbackChildren, renderLanes)

  }

  function updateSuspenseFallbackChildren(current, workInProgress, primaryChildren, fallbackChildren, renderLanes) {
    var mode = workInProgress.mode;
    var currentPrimaryChildFragment = current.child;
    var currentFallbackChildFragment = currentPrimaryChildFragment.sibling;
    var primaryChildProps = {
      mode: 'hidden',
      children: primaryChildren
    };
    var primaryChildFragment;

    if ( // In legacy mode, we commit the primary tree as if it successfully
    // completed, even though it's in an inconsistent state.
    (mode & ConcurrentMode) === NoMode && // Make sure we're on the second pass, i.e. the primary child fragment was
    // already cloned. In legacy mode, the only case where this isn't true is
    // when DevTools forces us to display a fallback; we skip the first render
    // pass entirely and go straight to rendering the fallback. (In Concurrent
    // Mode, SuspenseList can also trigger this scenario, but this is a legacy-
    // only codepath.)
    workInProgress.child !== currentPrimaryChildFragment) {
      var progressedPrimaryFragment = workInProgress.child;
      primaryChildFragment = progressedPrimaryFragment;
      primaryChildFragment.childLanes = NoLanes;
      primaryChildFragment.pendingProps = primaryChildProps;

      if ( workInProgress.mode & ProfileMode) {
        // Reset the durations from the first pass so they aren't included in the
        // final amounts. This seems counterintuitive, since we're intentionally
        // not measuring part of the render phase, but this makes it match what we
        // do in Concurrent Mode.
        primaryChildFragment.actualDuration = 0;
        primaryChildFragment.actualStartTime = -1;
        primaryChildFragment.selfBaseDuration = currentPrimaryChildFragment.selfBaseDuration;
        primaryChildFragment.treeBaseDuration = currentPrimaryChildFragment.treeBaseDuration;
      } // The fallback fiber was added as a deletion during the first pass.
      // However, since we're going to remain on the fallback, we no longer want
      // to delete it.


      workInProgress.deletions = null;
    } else {
      primaryChildFragment = updateWorkInProgressOffscreenFiber(currentPrimaryChildFragment, primaryChildProps); // Since we're reusing a current tree, we need to reuse the flags, too.
      // (We don't do this in legacy mode, because in legacy mode we don't re-use
      // the current tree; see previous branch.)

      primaryChildFragment.subtreeFlags = currentPrimaryChildFragment.subtreeFlags & StaticMask;
    }

    var fallbackChildFragment;

    if (currentFallbackChildFragment !== null) {
      fallbackChildFragment = createWorkInProgress(currentFallbackChildFragment, fallbackChildren);
    } else {
      fallbackChildFragment = createFiberFromFragment(fallbackChildren, mode, renderLanes, null); // Needs a placement effect because the parent (the Suspense boundary) already
      // mounted but this is a new fiber.

      fallbackChildFragment.flags |= Placement;
    }