how do i find out radio button length in netscape ?

[aapun]

hello folks,
i have a preliminary javascript question... please help me if possible.
I have a radio button named myRad in form myFrm.

<form name="myFrm">
<INPUT TYPE="radio" name = "myRad">
<INPUT TYPE="radio" name = "myRad">
<INPUT TYPE="radio" name = "myRad">
<INPUT TYPE="radio" name = "myRad">
<INPUT TYPE="radio" name = "myRad">
</form>


How do i get the number of elements in in myRad ?
This scripts works for me in IE:
alert(document.myFrm.myRad.length);

What do i do for netscape? I am running NS 4.75.


thank you in advance.