Merge pull request #2520 from etiktin/patch-2

Update browser-window.md

docs/api/browser-window.md

@@ -141,7 +141,7 @@ window.onbeforeunload = function(e) {
   // prompted to confirm the page unload, Electron gives developers more options.
   // Returning empty string or false would prevent the unloading now.
   // You can also use the dialog API to let the user confirm closing the application.
-  return false;
+  e.returnValue = false;
 };
 ```