Java Development Tools

Hi,
I am trying to have a javascript to render or not render the fields based on the drop down selection.
Here is the code that I have. It doesnot work. I am not sure how to set the 'rendered' property for a field to true or false. I am calling this on 'onchange' event of the drop down list values. Can anyone help me with this?

function formsubmit(value)
{
var render = false;
alert(value);
if(value == 0){

document.getElementById("form2:inputText20").rendered = true;
alert(document.getElementById("form2:inputText20").rendered);
return document.getElementById("form2:inputText20").rendered;
}


Thanks,
Priya