How to alert user, if radio box and check box is not selected

[traine]

If user do not click on any of these button, then how to alert to say select atleast 1 option for both the button(radio button & radio button)


Gender:

    <input type="radio" name="common" />Male
    <input type="radio" name="common" />Female

Select your Hobbies:

	Swimming<input type="checkbox" name="check1" />
	Playing<input type="checkbox" name="check2" />
	Driving<input type="checkbox" name="check3" />
	Riding<input type="checkbox" name="check4" />

[Dormilich]

you could either define a default value (via the checked attribute) or loop over each group showing the alert, if every .checked property is false.