From ecc40315b35aa43f17b6153e89f7118f7b414570 Mon Sep 17 00:00:00 2001
From: Andrea Giammarchi <andrea.giammarchi@gmail.com>
Date: Wed, 3 May 2023 10:00:35 +0200
Subject: [PATCH] Fix #1427 - Avoid multiple initialization of the same node
 (#1433)

---
 pyscriptjs/src/components/pyscript.ts | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/pyscriptjs/src/components/pyscript.ts b/pyscriptjs/src/components/pyscript.ts
index 3391b933..428f47dc 100644
--- a/pyscriptjs/src/components/pyscript.ts
+++ b/pyscriptjs/src/components/pyscript.ts
@@ -11,6 +11,9 @@ import { InterpreterClient } from '../interpreter_client';
 
 const logger = getLogger('py-script');
 
+// used to flag already initialized nodes
+const knownPyScriptTags: WeakSet<HTMLElement> = new WeakSet();
+
 export function make_PyScript(interpreter: InterpreterClient, app: PyScriptApp) {
     /**
      * A common <py-script> VS <script type="py"> initializator.
@@ -64,6 +67,10 @@ export function make_PyScript(interpreter: InterpreterClient, app: PyScriptApp)
         _fetchSourceFallback = () => htmlDecode(this.srcCode);
 
         async connectedCallback() {
+            // prevent multiple initialization of the same node if re-appended
+            if (knownPyScriptTags.has(this)) return;
+            knownPyScriptTags.add(this);
+
             // Save innerHTML information in srcCode so we can access it later
             // once we clean innerHTML (which is required since we don't want
             // source code to be rendered on the screen)
@@ -88,6 +95,10 @@ export function make_PyScript(interpreter: InterpreterClient, app: PyScriptApp)
 
         // bootstrap with the same connectedCallback logic any <script>
         const bootstrap = (script: PyScriptElement) => {
+            // prevent multiple initialization of the same node if re-appended
+            if (knownPyScriptTags.has(script)) return;
+            knownPyScriptTags.add(script);
+
             const pyScriptTag = document.createElement('py-script-tag') as PyScript;
 
             // move attributes to the live resulting pyScriptTag reference