promises.js

var greeting;
var readGreetingFromFileSync = function(){
  return 'Hello, ';
};

var getUserId = function(){
  return new Promise(function(resolve){
    setTimeout(function(){
      resolve(2);
    },100);
  });
};

var getUserFullName = function(id){
  var map = {
    1: 'shidhin',
    2: 'some one'
  };
  return new Promise(function(resolve,reject){
    setTimeout(function(){
      resolve(map[id]);
    },1000);
  });
};

var displayGreeting = function(name){
  console.log(greeting+name);
};

getUserId()
  .then(getUserFullName)
  .then(displayGreeting)
  .then(function(){
    console.log('The greeting was: ', greeting);
  });

greeting = readGreetingFromFileSync();