In a form if i have a radio box say yes n no... on clicking on yes i want a text area to pop up
how do i do this

hmmm i din get it there!!!
pl can u explain on how i can fo it

Asumming you have a hidden text area with the id "txarea" and a radio button with the is "rdbtn":

function onradiobuttonclick(){
var radiobutton = document.getElementById("rdbtn");
if (radiobutton.checked){
document.getElementById("txarea").style.visibility = "visible";
}
}

Asumming you have a hidden text area with the id "txarea"

How can you have a hidden text area ?

<input type="hidden" id="txarea" value="something here" />

Can't it be hidden with CSS? (visibility:hidden)

a text box that is hidden with CSS is not a hidden form field. Semantically, obviously, but technically, no.

@ ShawnCplus, the code you have mentioned gives a hidden textbox and not a textarea !

@scru, Hmm..Thats can be done. But if you apply css to it, then obviously, it will hide the textarea again if the page is reloaded.

i am not able to do tat ! pl help

I think AJAX is helpfull to view aqnd hide the text area