How to use a javascript variable in CFM page?

Question

I have a code in coldfusion pop up, the parent page has the variable which I intend to use in my CFM page.

I am able to get the variable in jacascript through the following:

<script type="text/javascript">
var selectedUserIdForPassword = $('#selectedUsers').val();
</script>

selectedUsers variable is in parent CFM page of the pop up, now I want to use this javascript variable in a query in the pop up's CFM page.

Please suggest.

Thanks in advance.