How to override JavaScript web api Notification object

Question

I have a scenario where I need to toggle notifications on and off for a webpage that is loaded in a webview inside an electron window. To do that I have injected a preload file inside the webview that overrides the Notification object like this.

window.oldNotification = window.Notification;
window.Notification = function() {
    let notificationEnabled = localStorage.getItem('notification-permissions') === 'true';
    if (notificationEnabled) {
        new window.oldNotification(...arguments);
    }
};

I am enabling and disabling notifications by changing a local storage variable.

The issue is that the webpage that I want to control is using Notification.permission method (refer this). Now my new Notification object has no permission property on it. I am not able to override the Notification object in a way where I can update its constructor so that I can disable the notification and also have other properties of the original Notification object.

Is there a way to achieve this or is this not possible at all? Any help or suggestion is absolutely welcome.

Answer 1

You can easily emulate Notification API

window.Notification = function() {
  const notificationEnabled = Notification.permission === 'granted';
  return notificationEnabled ? new window.oldNotification(...arguments) : {};
};

Object.defineProperty(Notification, 'permission', {
  get() {
    return localStorage.getItem('notification-permissions') === 'true' ? 'granted' : 'denied';
  }
});

Notification.requestPermission = (callback) => {
  if (typeof callback === 'function') {
    callback(Notification.permission);
  }

  return Promise.resolve(Notification.permission);
};