How does Facebook send notifications without tab

问题:

1. Go to facebook and allow HTML5 Desktop Notification for it.
2. Close facebook tab.
3. Ask somebody to write you message on facebook.

Now u see the notification from facebook while facebook site isn't open. HOW?

回答1:

Facebook uses the Push Notifications API: https://www.w3.org/TR/push-api/

More information:

• https://developers.google.com/web/fundamentals/push-notifications/
• https://developers.google.com/web/fundamentals/getting-started/push-notifications/