Javascript validating radio button

[jds580s]

I've done some validation on javascript buttons before, however I can't seem to get on the right track in zen-cart. I think it's because the names of the radio button groups are arrays.

For instance if my radio buttons looks like this:
<input name="id[1]" type="radio" value="1" />
<input name="id[1]" type="radio" value="2" />
<input name="id[1]" type="radio" value="3" />

and I'm calling a validation function with:
if (!validateRadiobutton(document.cart_quantity.id[1])) errs += 1;

Javascript doesn't seem to like the name being an array
If I change the html names to:
<input name="test" type="radio" value="1" />
<input name="test" type="radio" value="2" />
<input name="test" type="radio" value="3" />

and call the function with:
if (!validateRadiobutton(document.cart_quantity.test)) errs += 1;

it works just fine.

Any idea how to properly pass the "id[1]" as the name to javascript?

Thanks so much for any help!

[jds580s]

pardon my javascript syntax ineptitude.
For future reference the correct function call would have been

if (!validateRadiobutton(document.cart_quantity['id[1]'])) errs += 1;
not
if (!validateRadiobutton(document.cart_quantity.id[1])) errs += 1;