I'm building a MERN stack app. I'm trying to implement notification with Socket. IO.(I am a beginner for Socket. IO) My scenario is like this, it's an e-commerce website. I'm trying to send a notification to the seller if a buyer adds that product to their favorite list. If the seller is offline, can we save that favorite added notification, and can we indicate that notification using Socket.io after the seller comes online?

(As an example on Facebook we can see liked notifications when we go online.)

For that case should I send that notification details to the backend after that can I save it in my database or is there any feature to save that notification in Socket.io with a connection with the database?

Thanks, any help is appreciated!