function double(x) {

  return new Promise((resolve, reject) => {

    setTimeout(() => {

      return resolve(x*2);

    }, 1000);

  });

}

​

function triple(x) {

  return new Promise((resolve, reject) => {

    setTimeout(() => {

      return resolve(x*3);

    }, 1000);

  });

}

​

double(2).bind({})

.then(function (result) {

  this.double = result; // store result here

  return triple(2);

})

.then(function (result) {

  console.log('double:', this.double);

  console.log('triple:', result);

  console.log('sum:', this.double + result);

})

.catch((err) => {

  console.log(err.message);

});