window.safari.pushNotification Polyfill

polyfill.ts

// Writing a polyfill for window.safari.pushNotification.
// Source https://developer.apple.com/library/archive/documentation/NetworkingInternet/Conceptual/NotificationProgrammingGuideForWebsites/PushNotifications/PushNotifications.html

(() => {
  type Permission = 'default' | 'denied' | 'granted';

  class SafariRemoteNotification {
    permission(websitePushID: string) {
      return new SafariRemoteNotificationPermission(null, 'default')
    }
    requestPermission(url: string, websitePushID: string, userInfo: any, callback: (permission: SafariRemoteNotificationPermission) => void) {
      callback(new SafariRemoteNotificationPermission(null, 'denied'));
    }
  }

  class SafariRemoteNotificationPermission {
    constructor(readonly deviceToken: string | null, readonly permission: Permission) {
      this.deviceToken = deviceToken;
      this.permission = permission;
    }
  }

  const safari: any = (window as any).safari = {};
  safari.pushNotification = new SafariRemoteNotification();
})()

Another way of doing it: https://github.com/duckduckgo/content-scope-scripts/blob/4e73476b5188b28b8cd7e269ea3752b3120bb627/src/features/web-compat.js#L39-L92