Eliminate the possibility of a single render_widget output from keeping a view of prior renders (#196)

Author: cpsievert

CHANGELOG.md

@@ -5,6 +5,10 @@ All notable changes to shinywidgets will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [UNRELEASED]
+
+* Eliminate the possibility of a single `@render_widget` output from keeping a view of prior renders. (#196)
+
 ## [0.6.1] - 2025-05-21
 
 * Fixed an issue introduced by v0.6.0 where cleanup wasn't happening when it should be. (#195)

js/src/output.ts

@@ -103,6 +103,14 @@ class IPyWidgetOutput extends Shiny.OutputBinding {
     const view = await manager.create_view(model, {});
     await manager.display_view(view, {el: el});
 
+    // Don't allow more than one .lmWidget container, which can happen
+    // when the view is displayed more than once
+    // N.B. It's probably better to get view(s) from m.views and .remove() them,
+    // but empirically, this seems to work better
+    while (el.childNodes.length > 1) {
+      el.removeChild(el.childNodes[0]);
+    }
+
     // The ipywidgets container (.lmWidget)
     const lmWidget = el.children[0] as HTMLElement;