Function postorder

packages/react-stately/src/data/useTreeData.ts:528–552

(child)

  }

  function postorder(child) {
    // remove items and update the tree from the leaves and work upwards toward the root, this way
    // we don't copy child node references from parents inadvertently
    if (keyArray.includes(child.key)) {
      removedItems.push({...newMap.get(child.key)!, parentKey: toParent?.key ?? null});
      let {items: nextItems, nodeMap: nextMap} = updateTree(
        newItems,
        child.key,
        () => null,
        newMap
      );
      newItems = nextItems;
      newMap = nextMap;
    }
    // decrement the index if the child being removed is in the target parent and before the target index
    // the root node is special, it is null, and will not have a key, however, a parentKey can still point to it
    if (
      (child.parentKey === toParent || child.parentKey === toParent?.key) &&
      keyArray.includes(child.key) &&
      (toParent?.children ? toParent.children.indexOf(child) : items.indexOf(child)) <
        originalToIndex
    ) {
      toIndex--;
    }
  }

  traversal({children: items}, {inorder, postorder});