dispatch.js

var dispatch  = [{ referrer: 'referrer1.com', group_id: 1 }, { referrer: 'referrer2.com', group_id: 2 }, { referrer: 'referrer3.com', group_id: 3 }]
var results   = $.grep(dispatch, function(e){ return e.referrer == document.referrer; });

if(results.length == 0) {
   _slaask.init("xxxxxxxxxxxxxxxxxxxxxxxxxxxx");
} else {
   _slaask.init("xxxxxxxxxxxxxxxxxxxxxxxxxxxx", { user_group_id: results[0].group_id });
}