[JavaScript] Getting Option Index based on Option Value

I am trying to get the index of an Option element
in a Select list based on its Value. 
This was my first (unsuccessful) guess:

document.forms[ 0 ].billingstate.options["CA"].index

How do reference this? I can't seem to find an example
in the O'reilly rhino book.

Any help: vastly appreciated.
_Ken Creason
webmaster(at)fcs.net

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