prepopulate radio button

This script prepopulates the select box, state, but not the radio button, tobacco.

<script language="javascript" type="text/javascript">

function prepop()
{
document.long_form.state.value="<?php echo $_SESSION['state']; ?>";
document.long_form.tobacco.value="<?php echo $_SESSION['tobacco']; ?>";
}
window.onload=prepop;

</script>

Code (markup):

The value for tobacco, yes or no, shows on the page with view source, so the value got to the page, but I can't find how to address a radio button so the delivered value is preselected, and I'm out of ideas.

Any suggestions?

 

i believe it is .selectedIndex is what you need.

 

Thanks for your interest, ccoonen. selectedIndex is used with arrays in drop down boxes.

I now have the answer.

Here is the solution for prepopulating a radio button that receives its value from a php session (substitute input code accordingly for any other source):

var tob; 
var tabac="<?php echo $_SESSION['tobacco']; ?>"; 
{
if (tabac=="yes") 
{tob="0"} 

else if (tabac=="no")
{tob="1"} 

document.long_form.tobacco[tob].checked = true;

Code (markup):

This line is then not needed for the radio button:

document.long_form.tobacco.value="<?php echo $_SESSION['tobacco']; ?>";

Code (markup):

Now the text boxes (don't need javascript), drop down boxes, AND radio buttons are all prepopulated.

Resolved!