XML : XSLT using javascript variables as 'select' values

I'm trying to write a dynamically sorting table. For this I want to use a javascript variable which will contain the information of the sort select value. I'm new with xml and I was wondering how (and if) it is possible to use a js value inside xsl.

Like:

  <script>var x = "gangsters"</script>  ...  <xsl:sort select="x"....></>    

Would make the table sort by "gangsters".

Any help would be strongly appreciated.