I have looked on google and can not get anything to work

I know there is a javascript alert box, but I would like a javascript confirmation box

I presume on a server side buttons onclientclick that the javascript could pop up a confirmation box and if you press ok the onclick event is passed through as normal to the server, and that if you press no or cancel that the buttons click event will not be submitted to the server

can somebody please give me some javascript code etc to sort out this problem please ?