How can I check whether a radio button is selected with JavaScript?

Question

I have two radio buttons within an HTML form. A dialog box appears when one of the fields is null. How can I check whether a radio button is selected?

Answer 1

Here is the solution which is expanded upon to not go ahead with submission and send an alert if the radio buttons are not checked. Of course this would mean you have to have them unchecked to begin with!

if(document.getElementById('radio1').checked) {
} else if(document.getElementById('radio2').checked) {
} else {
  alert ("You must select a button");
  return false;
}

Just remember to set the id ('radio1','radio2' or whatever you called it) in the form for each of the radio buttons or the script will not work.