A very simple example showing deferrals and promises using jQuery

deferralsPromises

// Setup a global scopped timer variable
var timer;
  
// Create a named function expression
var yourPromise = getBeer();

// Execute this code when the promise is done
yourPromise.done(function(message) {
  console.log('done. ' + message);
});

// Execute this code when update notifications are recieved
yourPromise.progress(function(message) {
    console.log('progress: ' + message);
});


// Our worker function: returns a deferred promise
function getBeer() {
  // Setup a deferred object
  var deferred = $.Deferred();
 
  // Notify our progress listener of our progress every second
  timer = setInterval(function() {
    deferred.notify('Still out getting beer');
  }, 1000);
  
  // After 10 seconds clear our notification and resolve our promise
  setTimeout(function() {
     clearInterval(timer);
     deferred.resolve('Here is your beer');
  }, 10000);
  
  // Return our deferred promise
  return deferred.promise();
}