For realtime update of a page or a part of a page, you must be using "Comet" technology, such as forever-iframe with script tag injection, long polling of a server, JSON polling of a server etc.

http://en.wikipedia.org/wiki/Comet_(programming)

Also HTML5 WebSockets is a newer option: http://www.websocket.org/quantum.html

Either way you must fall back to long polling or JSON polling too just in case.

For example, Socket.io for Node.js does this: http://socket.io/

For realtime update of a page or a part of a page, you must be using "Comet" technology, such as forever-iframe with script tag injection, long polling of a server, JSON polling of a server etc.

Also HTML5 WebSockets is a newer option.

Either way you must fall back to long polling or JSON polling too just in case.

For example, Socket.io for Node.js does this automatically.