Update App.js

src/App.js

@@ -20,6 +20,12 @@ let textInput
 export default function App() {
 
     useLayoutEffect(() => {
+
+        window.addEventListener("beforeunload", e => {
+            e.preventDefault()
+            e.returnValue = ""
+        })
+
         canvas = document.getElementById("canvas")
         context = canvas.getContext("2d")
         clearScreen("rgb(255, 255, 255)")
@@ -548,6 +554,7 @@ export default function App() {
                     </div>
                 </div>
             </div>
+
         </div>
     );
 }