The type property represents the button's TYPE HTML attribute. For this object, it is always radio.
<html> <head> <title> Example of the radio type property</title> </head> <body> <form name="form1"> <input type="radio" name=button1>Box 1 <br><br> <input type="button" value="Get Button Type" onClick='alert("The button type is: " + document.form1.button1.type)'> </form> </body> </html>