jQuery promise pattern

pattern.js

 function doStuff(flag) {
     var deferred = $.Deferred();
     var err = null,
         data = null;
     if (flag) {
         setTimeout(function() {
             data = ["2", "2"];
             deferred.resolve(err, data);
         }, 5 * 1000)
     } else {
         setTimeout(function() {
             err = "Error msg goes here";
             data = null;
             deferred.resolve(err, data);
         }, 5 * 1000)
     }
     return deferred.promise();
 }
 (function() {
     var promiseTrue = doStuff(true);
     console.log("promiseTrue created..");
     promiseTrue.done(function(err, data) {
         console.log(err);
         console.log(data);
     });
     var promiseFalse = doStuff(false);
     console.log("promiseFalse created..");
     promiseFalse.done(function(err, data) {
         console.log(err);
         console.log(data);
     });
 })();