// i have some global variables defined which are visible throughout the whole site
  var searchType = ['category_id', 'theme_id', 'mood_id', 'instrument_id'];
  var searchSpeedSelection = '0';
// these variables _must_ be global, because they are accessed from different JS-functions / event-handlers

// now i have 2 possibilities:
// 1. i pass these variables to my event handlers like this:

jQuery(".foo").click(function(event){
  setTracklistCount(globalSelectionArray, searchSpeedSelection)
}

// advantage: it is clearer what is happening

// 2. i just use them like this:

jQuery(".foo").click(function(event){
  setTracklistCount();
}
// and within "setTracklistCount()" i simply refer to them

function setTracklistCount(){
  if (searchSpeedSelection.....)
}
// advantage: i dont have to pass in a possibly very big list of already global variables
// disadvantag: less clear