Dynamic notifications pop up
Facebook calls an AJAX endpoint every few seconds to keep the client-side UI fresh. The payload from this endpoint contains updates for ticker, newsfeed, notifications, messages and various other statuses. You can view this by opening Facebook in Google Chrome and looking at the network tab in Chrome Developer Tools.
How is the dynamic notification updates are displayed in facebook.Also here at stackoverflow, why isn't the notifications pop up immediately as notifications arises.They aren't displayed until i refresh the page.