Cancellable promise with bluebird

cancellable_promise-bluebird.js

import Promise from 'Bluebird';

function updateUser() {
  return new Promise((resolve, reject, onCancel) => {
    let cancelled = false;

    // you need to config Bluebird to have cancellation
    // http://bluebirdjs.com/docs/api/promise.config.html
    onCancel(() => {
      cancelled = true;
      reject({ reason: 'cancelled' });
    });

    return fetchData()
      .then(wrapWithCancel(updateUserData))
      .then(wrapWithCancel(updateUserAddress))
      .then(wrapWithCancel(updateMarketingData))
      .then(resolve)
      .catch(reject);

    function wrapWithCancel(fn) {
      // promise is resolved only with one parameter
      return (data) => {
        if (!cancelled) {
          return fn(data);
        }
      };
    }
  });
}

const promise = updateUser();
// wait some time...
promise.cancel(); // user will be updated any way