promise_chain.js

const promise = value => {
  return new Promise(resolve => {
    setTimeout(
      resolve.bind(this, value),
      600
    );
  });
}

const show = value => {
  console.log(value);
  return value;
}

const increment = value => value + 1;

promise(1000).then(show).then(increment)
  .then(promise).then(show).then(increment)
  .then(promise).then(show);
// output:
// 1000
// 1001
// 1002