From 71aea5352bf07b27f5b8f991b46c4aa3d0b70554 Mon Sep 17 00:00:00 2001
From: Jason Park <parkjs814@gmail.com>
Date: Mon, 10 Dec 2018 03:02:20 -0500
Subject: [PATCH] Add window.onbeforeunload

---
 src/frontend/components/App/index.jsx | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/frontend/components/App/index.jsx b/src/frontend/components/App/index.jsx
index 3192bcd..fc0cb72 100644
--- a/src/frontend/components/App/index.jsx
+++ b/src/frontend/components/App/index.jsx
@@ -75,11 +75,14 @@ class App extends BaseComponent {
 
   toggleHistoryBlock(enable = !this.unblock) {
     if (enable) {
+      const warningMessage = 'Are you sure you want to discard changes?';
+      window.onbeforeunload = () => this.isSaved() ? undefined : warningMessage;
       this.unblock = this.props.history.block((location) => {
         if (location.pathname === this.props.location.pathname) return;
-        if (!this.isSaved()) return 'Are you sure want to discard changes?';
+        if (!this.isSaved()) return warningMessage;
       });
     } else {
+      window.onbeforeunload = undefined;
       this.unblock();
       this.unblock = undefined;
     }
-- 
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