1 files changed, 24 insertions, 0 deletions
diff --git a/app/assets/javascripts/pages/projects/merge_requests/edit/check_form_state.js b/app/assets/javascripts/pages/projects/merge_requests/edit/check_form_state.js
new file mode 100644
index 00000000000..74178ab96e3
--- /dev/null
+++ b/app/assets/javascripts/pages/projects/merge_requests/edit/check_form_state.js
@@ -0,0 +1,24 @@
+import { serializeForm } from '~/lib/utils/forms';
+
+const findForm = () => document.querySelector('.merge-request-form');
+const serializeFormData = () => JSON.stringify(serializeForm(findForm()));
+
+export default () => {
+  const oldFormData = serializeFormData();
+
+  const compareFormData = (e) => {
+    const newFormData = serializeFormData();
+
+    if (oldFormData !== newFormData) {
+      e.preventDefault();
+      // eslint-disable-next-line no-param-reassign
+      e.returnValue = ''; // Chrome requires returnValue to be set
+    }
+  };
+
+  window.addEventListener('beforeunload', compareFormData);
+
+  findForm().addEventListener('submit', () =>
+    window.removeEventListener('beforeunload', compareFormData),
+  );
+};