> ## Documentation Index
> Fetch the complete documentation index at: https://docs.speckle.systems/llms.txt
> Use this file to discover all available pages before exploring further.

# Backwards Compatibility

> For **backwards compatibility** reasons we provide a built-in legacy implementation that emulates the old API precisely. Please note that this is meant as a temporary measure which will eventually become naturally obsolete. For this purpose, this migration guide entry will describe moving from any older viewer version to 2.18 *while using the legacy implementation*

* `Viewer` or `DebugViewer` instances are replaced by `LegacyViewer`
* The `hits` field from `SelectionEvent` now holds the hit node and hit point.
  ```typescript theme={null}
  type SelectionEvent = {
    multiple: boolean;
    event?: PointerEvent;
    hits: Array<{
      node: TreeNode;
      point: Vector3;
    }>;
  };
  ```
* The synchronous `loadObject` was removed. Please use `loadObjectAsync` which  works the same way