onBlur() for textbox

Hi am a newbie to web, i have a doubt ,i trying to fetch data from server before the submit of the form. When i give an id in the textbox ,when the textbox get ouBlur() i want to fetch data from server.

Simply write a SUBMIT handler that fetches the data from the server before doing the actual form submit. You don't have to rely on a 'built in' submit from a form. Just provide a button (a normal button, not a submit button) that calls a function when pressed. In that function, do your data retrieval from the server then when you are ready, call yourFormName.sumbmit() to submit the entire form to the server. I use this technique quite often, actually I don't think I ever use a 'standard form submit'. I always do validation etc before sending the form contents to the server.