Move PageExitPrevention to its own file

ext/bg/js/page-exit-prevention.js

@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2019  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+class PageExitPrevention {
+  constructor() {
+  }
+
+  start() {
+      PageExitPrevention._addInstance(this);
+  }
+
+  end() {
+      PageExitPrevention._removeInstance(this);
+  }
+
+  static _addInstance(instance) {
+      const size = PageExitPrevention._instances.size;
+      PageExitPrevention._instances.set(instance, true);
+      if (size === 0) {
+          window.addEventListener('beforeunload', PageExitPrevention._onBeforeUnload);
+      }
+  }
+
+  static _removeInstance(instance) {
+      if (
+          PageExitPrevention._instances.delete(instance) &&
+          PageExitPrevention._instances.size === 0
+      ) {
+          window.removeEventListener('beforeunload', PageExitPrevention._onBeforeUnload);
+      }
+  }
+
+  static _onBeforeUnload(e) {
+      if (PageExitPrevention._instances.size === 0) {
+          return;
+      }
+
+      e.preventDefault();
+      e.returnValue = '';
+      return '';
+  }
+}
+
+PageExitPrevention._instances = new Map();

ext/bg/js/settings.js

@@ -222,52 +222,6 @@ async function onReady() {
 $(document).ready(() => onReady());
 
 
-/*
- * Page exit prevention
- */
-
-class PageExitPrevention {
-    constructor() {
-    }
-
-    start() {
-        PageExitPrevention._addInstance(this);
-    }
-
-    end() {
-        PageExitPrevention._removeInstance(this);
-    }
-
-    static _addInstance(instance) {
-        const size = PageExitPrevention._instances.size;
-        PageExitPrevention._instances.set(instance, true);
-        if (size === 0) {
-            window.addEventListener('beforeunload', PageExitPrevention._onBeforeUnload);
-        }
-    }
-
-    static _removeInstance(instance) {
-        if (
-            PageExitPrevention._instances.delete(instance) &&
-            PageExitPrevention._instances.size === 0
-        ) {
-            window.removeEventListener('beforeunload', PageExitPrevention._onBeforeUnload);
-        }
-    }
-
-    static _onBeforeUnload(e) {
-        if (PageExitPrevention._instances.size === 0) {
-            return;
-        }
-
-        e.preventDefault();
-        e.returnValue = '';
-        return '';
-    }
-}
-PageExitPrevention._instances = new Map();
-
-
 /*
  * Appearance
  */

ext/bg/settings.html

@@ -876,6 +876,7 @@
         <script src="/bg/js/dictionary.js"></script>
         <script src="/bg/js/handlebars.js"></script>
         <script src="/bg/js/options.js"></script>
+        <script src="/bg/js/page-exit-prevention.js"></script>
         <script src="/bg/js/profile-conditions.js"></script>
         <script src="/bg/js/templates.js"></script>
         <script src="/bg/js/util.js"></script>