legolas

I got it to work now. One of the radiobuttons and the textbox needed each an id

<input type="radio" name="mybox" value="1" id="mybox1" checked="checked" />No
<input type="radio" name="mybox" value="2" />Yes
<input type="text" size="8" name="mytext" id="mytext" />

On submitting the form

<input type="submit" name="Submit" onClick='javascript:setRequired()' value="Submit" />

a Javascript was called

function setRequired() {
var s = document.getElementById("mybox1");
if (s.checked) {
$("#mytext").removeAttr('required');
} else {
$("#mytext").attr('required', '');
}

}

check for more details:

http://stackoverflow.com/questions/18770369/how-to-set-html5-required-attribute-in-javascript

Thanks for replies!

I have a form with two radio buttons, line 1 and 2, and a text box on the third line

<input type="radio" name="mybox1" value="1" checked="checked" />No
<input type="radio" name="mybox2" value="2" />Yes
<input type="text" size="8" name="mytext" />

The requirement is:

If "No" is selected, the textbox must be empty on submitting the form.

If "Yes" is selected, the textbox on line 3 must not be empty on submitting the form.

So I cannot add the attribute 'required' in the third line, instead

I have to control it dynamically depending on the radio button selection.

How can I accomplish this?