Naive implementaion of referrer tracking

fromDomain

//-- Polyfill ---------------------------------------------------------
if ( !String.prototype.contains ) {
    String.prototype.contains = function() {
        return String.prototype.indexOf.apply( this, arguments ) !== -1;
    };
}

//-- Module -----------------------------------------------------------
(function(exports, document, undefined) {
  var namespace = 'tools';
    , makeReferrerTest =
        function(string) {
          return function() {
            return document
                    .referrer
                    .toLowerCase()
                    .contains(string);
          };
        }

    exports[namespace] = {
      makeReferrerTest: makeReferrerTest
    };
}(window, document)); 

var fromBilletto = tools.makeReferrerTest('billetto');

if(fromBilletto()) {
  // you count implementation Ajax,Ga what not
}