From 48ad4f65026f62543c90215f5fae0cab8ccc51f5 Mon Sep 17 00:00:00 2001
From: Brian Ward <bward@flatironinstitute.org>
Date: Tue, 30 Jul 2024 19:29:23 +0000
Subject: [PATCH] Confirm before unload if unsaved changes

---
 gui/src/app/Project/ProjectContextProvider.tsx | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/gui/src/app/Project/ProjectContextProvider.tsx b/gui/src/app/Project/ProjectContextProvider.tsx
index 27ffb4eb..3a930406 100644
--- a/gui/src/app/Project/ProjectContextProvider.tsx
+++ b/gui/src/app/Project/ProjectContextProvider.tsx
@@ -1,4 +1,8 @@
-import { initialDataModel, ProjectDataModel } from "@SpCore/ProjectDataModel";
+import {
+  initialDataModel,
+  modelHasUnsavedChanges,
+  ProjectDataModel,
+} from "@SpCore/ProjectDataModel";
 import {
   fetchRemoteProject,
   fromQueryParams,
@@ -47,9 +51,13 @@ const ProjectContextProvider: FunctionComponent<
 
   useEffect(() => {
     // as user reloads the page or closes the tab, save state to local storage
-    const handleBeforeUnload = () => {
+    const handleBeforeUnload = (e: BeforeUnloadEvent) => {
       const state = serializeProjectToLocalStorage(data);
       localStorage.setItem("stan-playground-saved-state", state);
+      if (modelHasUnsavedChanges(data)) {
+        e.preventDefault();
+        e.returnValue = true; // legacy
+      }
     };
     window.addEventListener("beforeunload", handleBeforeUnload);