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>