1 files changed, 29 insertions, 0 deletions
diff --git a/ext/bg/js/settings/settings-controller.js b/ext/bg/js/settings/settings-controller.js
index 87dea408..6479714d 100644
--- a/ext/bg/js/settings/settings-controller.js
+++ b/ext/bg/js/settings/settings-controller.js
@@ -26,6 +26,8 @@ class SettingsController extends EventDispatcher {
         super();
         this._profileIndex = profileIndex;
         this._source = yomichan.generateId(16);
+        this._pageExitPreventions = new Set();
+        this._pageExitPreventionEventListeners = new EventListenerCollection();
     }
 
     get source() {
@@ -109,6 +111,16 @@ class SettingsController extends EventDispatcher {
         return {index: this._profileIndex};
     }
 
+    preventPageExit() {
+        const obj = {end: null};
+        obj.end = this._endPreventPageExit.bind(this, obj);
+        if (this._pageExitPreventionEventListeners.size === 0) {
+            this._pageExitPreventionEventListeners.addEventListener(window, 'beforeunload', this._onBeforeUnload.bind(this), false);
+        }
+        this._pageExitPreventions.add(obj);
+        return obj;
+    }
+
     // Private
 
     _setProfileIndex(value) {
@@ -147,4 +159,21 @@ class SettingsController extends EventDispatcher {
         targets = this._setupTargets(targets, extraFields);
         return await api.modifySettings(targets, this._source);
     }
+
+    _onBeforeUnload(e) {
+        if (this._pageExitPreventions.size === 0) {
+            return;
+        }
+
+        e.preventDefault();
+        e.returnValue = '';
+        return '';
+    }
+
+    _endPreventPageExit(obj) {
+        this._pageExitPreventions.delete(obj);
+        if (this._pageExitPreventions.size === 0) {
+            this._pageExitPreventionEventListeners.removeAllEventListeners();
+        }
+    }
 }