How do you use variables inside of click functions.

How do you use variables inside of click functions.

I have some vars I wanna persist beyond the click function.  I declared them outside.   I'm not much of a java scriptie.  But as I understand you use var for local vars and you don't use var for globals.  I guess these are globals. 

  1. $(document).ready(function() {
         piecesUsed =  [];
         piecesAvailable =  ['NSW','WA','Queensland','Victoria','Tasmania','NZ','SA', 'NT'];
         currentPiece = '';
       
        $('#ask').click( function() {
            if (currentPiece == '') {
                i = Math.floor(Math.random() *  length(piecesAvailable));
                currentPiece = piecesAvailable[i];
            }
            playTrack('http://localhost/GeoP-Test/audio/' + currentPiece  + '.mp3');
        });

        //more jquery stuff
    });













When I go into the Firebug debugger everything goes to hell when it gets to the Math line.  I can't even get the Error console to see if there's something wrong.  Pls tell me what I'm doing wrong here.  Thanks!