Radio buttons come in groups. They are bound together as a group by having the same name:
<INPUT TYPE="radio" NAME="rad" VALUE="radio_button1">
<INPUT TYPE="radio" NAME="rad" VALUE="radio_button2">
<INPUT TYPE="radio" NAME="rad" VALUE="radio_button3">
<INPUT TYPE="radio" NAME="rad" VALUE="radio_button4">
A particular radio button can be preselected with the "CHECKED" attribute:
<INPUT TYPE="radio" NAME="rad" Value="rad_button1" CHECKED>
Or with Javascript:
form.rad[0].checked = true; // sets to first button in the rad group
Finding the selected radio button with Javascript:
function test_radio_button (form){
for (Count = 0; Count < 3; Count++) {
if (form.rad[Count].checked)
break;
}
alert ("Button " + Count + " is selected");
}