The focus() method sets the focus to the radio button.
<html> <head> <title> Example of the radio focus method</title> </head> <body> <form name="form1"> <input type="radio" name=button1>Box 1 <br> <input type="radio" name=button2>Box 2 <br><br> <input type="button" value="Set Focus to Box 1" onClick='document.form1.button1.focus()'> </form> </body> </html>