gistfile1.js

var data;
(function(){
   var x = new XMLHttpRequest();
   data["abc"] = {};
   data["abc"]["def"] = x;
   data["abc"]["wxy"] = x;
})();

(function(){
   data["abc"]["foobar"] = function(){
      if (data["abc"]["wxy"].readyState == 4) {
         alert(data["abc"]["wxy"].responseText);
      }
   }
})();

(function(){
   data["abc"]["def"].onreadystatechange = data["abc"]["foobar"];
})();