feat: remove visibilityjs (#10870)

* feat: remove visibilityjs

* fix: actually remove require

* style: add a newline

* style: forgot a semicolon

* style: accidently removed trailing newline

* fix: move property declaration to its actual previous place

install/package.json

@@ -134,7 +134,6 @@
         "toobusy-js": "0.5.1",
         "uglify-es": "3.3.9",
         "validator": "13.7.0",
-        "visibilityjs": "2.0.2",
         "webpack": "5.74.0",
         "webpack-merge": "5.8.0",
         "winston": "3.8.1",

public/src/app.js

@@ -9,7 +9,6 @@ require('jquery-form');
 window.utils = require('./utils');
 require('timeago');
 
-const Visibility = require('visibilityjs');
 const Benchpress = require('benchpressjs');
 Benchpress.setGlobal('config', config);
 
@@ -19,7 +18,11 @@ require('./ajaxify');
 
 app = window.app || {};
 
-app.isFocused = true;
+Object.defineProperty(app, 'isFocused', {
+	get() {
+		return document.visibilityState === 'visible';
+	}
+});
 app.currentRoom = null;
 app.widgets = {};
 app.flags = {};
@@ -95,10 +98,6 @@ if (document.readyState === 'loading') {
 			app.newTopic();
 		});
 
-		Visibility.change(function (event, state) {
-			app.isFocused = state === 'visible';
-		});
-
 		registerServiceWorker();
 
 		require([