[jQuery] Ajax enabled Links/Forms and AutoRefresh

[anyz]

I'm looking for following ajax functionaliaties. Can you please point
me to some example or correct page in documentation.

1- Ajax enabled Link (a) that on click fetch data from server
(database) and refresh an area of page with new data

2- Ajax enabled form, that on submit does same as above in point#1

3- Automatically sends an ajax call to server after given number of
seconds, gets data from server(database) and refresh a area on page.
Just like pop-up alerts used by Outlook

[jQuery] ajax and links

[Tom Shafer]

is it possible to have the url and the data come from the link href
using the ajax funtions in jquery?