IME the oly effective way I have found is to post the JS
value (hidden form variable or otherwise) to another page to get it into ASP. Yes this requires another page however it does not have to have a user interface EG post > get value > redirect
There are loads of example of this on the www. Ask Google you will be suprised at how many pages detail exactly how to do this.
That example om_prakash has given you passes the variable the other way, clearly very easy to do this. BTW - As Joe says, you can not use ASP like you have in your second post
Wind is your friend