From 86f8b8991a46120f63afef52c8927efb39f9caca Mon Sep 17 00:00:00 2001
From: Simon Lydell <simon.lydell@gmail.com>
Date: Sat, 2 Aug 2025 21:57:09 +0200
Subject: [PATCH 1/2] Add hot reloading

This adds hot reloading support for `main : Html msg` programs.

It needs support in `Platform` in elm/core to work.
---
 src/Elm/Kernel/VirtualDom.js | 45 +++++++++++++++++++++++++++---------
 1 file changed, 34 insertions(+), 11 deletions(-)

diff --git a/src/Elm/Kernel/VirtualDom.js b/src/Elm/Kernel/VirtualDom.js
index 61e9003e..add36ff9 100644
--- a/src/Elm/Kernel/VirtualDom.js
+++ b/src/Elm/Kernel/VirtualDom.js
@@ -114,23 +114,46 @@ function _VirtualDom_createTNode(domNode)
 	};
 }
 
-var _VirtualDom_init = F4(function(virtualNode, flagDecoder, debugMetadata, args)
+var _VirtualDom_init = F3(function(virtualNode, flagDecoder, debugMetadata)
 {
 	// NOTE: this function needs __Platform_export available to work
 
-	/**__PROD/
-	var node = args['node'];
-	//*/
+	var init = function(args)
+	{
+		/**__PROD/
+		var node = args['node'];
+		//*/
+		/**__DEBUG/
+		var node = args && args['node'] ? args['node'] : __Debug_crash(0);
+		//*/
+
+		var sendToApp = function() {};
+		var tNode = _VirtualDom_createTNode(undefined);
+		var nextNode = _VirtualDom_render(virtualNode, sendToApp, tNode);
+		nextNode.elmTree = tNode;
+		node.parentNode.replaceChild(nextNode, node);
+		node = nextNode;
+
+		var app = {};
+
+		/**__DEBUG/
+		app.hotReload = function(hotReloadData)
+		{
+			node = _VirtualDom_applyPatches(node, virtualNode, hotReloadData.__$virtualNode, sendToApp);
+			virtualNode = hotReloadData.__$virtualNode;
+		};
+		//*/
+
+		return app;
+	};
+
 	/**__DEBUG/
-	var node = args && args['node'] ? args['node'] : __Debug_crash(0);
+	init.hotReloadData = {
+		__$virtualNode: virtualNode
+	};
 	//*/
 
-	node.parentNode.replaceChild(
-		_VirtualDom_render(virtualNode, function() {}, _VirtualDom_createTNode(undefined)),
-		node
-	);
-
-	return {};
+	return init;
 });
 
 

From 66fe2171254f4c284e6864ba2acaa972b7e16ff8 Mon Sep 17 00:00:00 2001
From: Simon Lydell <simon.lydell@gmail.com>
Date: Sun, 3 Aug 2025 15:35:00 +0200
Subject: [PATCH 2/2] Make it possible to stop an app

This adds `app.stop()` and `app.detachView()` for `main : Html msg` programs.
---
 src/Elm/Kernel/VirtualDom.js | 90 ++++++++++++++++++++++++++++++++++--
 1 file changed, 87 insertions(+), 3 deletions(-)

diff --git a/src/Elm/Kernel/VirtualDom.js b/src/Elm/Kernel/VirtualDom.js
index add36ff9..c56d7faf 100644
--- a/src/Elm/Kernel/VirtualDom.js
+++ b/src/Elm/Kernel/VirtualDom.js
@@ -134,7 +134,23 @@ var _VirtualDom_init = F3(function(virtualNode, flagDecoder, debugMetadata)
 		node.parentNode.replaceChild(nextNode, node);
 		node = nextNode;
 
-		var app = {};
+		var stopped = false;
+		var detachView = function()
+		{
+			// Make a second call to `app.detachView` do nothing.
+			if (stopped)
+			{
+				return node;
+			}
+			stopped = true;
+			_VirtualDom_removeAllEventListeners(node);
+			return node;
+		};
+
+		var app = {
+			detachView: detachView,
+			stop: detachView
+		};
 
 		/**__DEBUG/
 		app.hotReload = function(hotReloadData)
@@ -613,7 +629,9 @@ function _VirtualDom_render(vNode, eventNode, tNode)
 
 	if (_VirtualDom_divertHrefToApp && vNode.__tag == 'a')
 	{
-		domNode.addEventListener('click', _VirtualDom_divertHrefToApp(domNode));
+		var listener = _VirtualDom_divertHrefToApp(domNode);
+		domNode.elmAf = listener;
+		domNode.addEventListener('click', listener);
 	}
 
 	_VirtualDom_applyFacts(domNode, eventNode, {}, vNode.__facts);
@@ -1994,7 +2012,9 @@ function _VirtualDom_virtualizeHelp(node, tNode)
 
 		if (_VirtualDom_divertHrefToApp && node.localName === 'a')
 		{
-			node.addEventListener('click', _VirtualDom_divertHrefToApp(node));
+			var listener = _VirtualDom_divertHrefToApp(node);
+			node.elmAf = listener;
+			node.addEventListener('click', listener);
 		}
 	}
 
@@ -2077,3 +2097,67 @@ function _VirtualDom_dekey(keyedNode, tNode)
 		__descendantsCount: keyedNode.__descendantsCount
 	};
 }
+
+function _VirtualDom_removeAllEventListeners(rootDomNode)
+{
+	var tNode = rootDomNode.elmTree;
+
+	// Allow mounting another Elm app on this DOM node.
+	delete rootDomNode.elmTree;
+
+	_VirtualDom_removeAllEventListenersHelp(tNode);
+}
+
+function _VirtualDom_removeAllEventListenersHelp(tNode)
+{
+	var domNode = tNode.__domNode;
+	var children = tNode.__children;
+
+	// Allow the DOM nodes to be virtualized by another Elm app.
+	if (domNode.nodeType === 1)
+	{
+		domNode.setAttribute(_VirtualDom_markerProperty, '');
+	}
+
+	if (domNode.elmAf)
+	{
+		domNode.removeEventListener('click', domNode.elmAf);
+		delete domNode.elmAf;
+	}
+
+	var allCallbacks = domNode.elmFs;
+	if (allCallbacks)
+	{
+		for (var key in allCallbacks)
+		{
+			domNode.removeEventListener(key, allCallbacks[key]);
+		}
+		delete domNode.elmFs;
+	}
+
+	for (var key in children)
+	{
+		_VirtualDom_removeAllEventListenersHelp(children[key]);
+	}
+}
+
+// Used by `_Debugger_document` to remove the corner when shutting down.
+function _VirtualDom_removeLastElmChild(rootDomNode)
+{
+	var tNode = rootDomNode.elmTree;
+	var children = tNode.__children;
+	var childNodes = rootDomNode.childNodes;
+	for (var i = childNodes.length - 1; i >= 0; i--)
+	{
+		var childDomNode = childNodes[i];
+		for (var key in children)
+		{
+			if (childDomNode === children[key].__domNode)
+			{
+				rootDomNode.removeChild(childDomNode);
+				delete children[key];
+				return;
+			}
+		}
+	}
+}