promise.js

var p = new Promise(function(resolve, reject){
  resolve(1);
});
p.then(function(value){               //1st then
  console.log(value);
  return Promise.resolve(value*2);
}).then(function(value){              //2nd then
  console.log(value);
  return Promise.resolve(undefined)
}).then(function(value){              //3rd then
  console.log(value);
  return Promise.resolve('resolve');
}).then(function(value){              //4th then
  console.log(value);
  return Promise.reject('reject');
  
}).then(function(value){              //5th then
  console.log('resolve: '+ value);
}, function(err){
  console.log('reject: ' + err);
})