Cancellable promise helper

Cancellable.js

// https://github.com/mehiel/router/blob/58c7aa4d0be87b6c4aad9643f168058f42eafcd7/src/lib/utils.js#L261
// makeCancelable as in https://reactjs.org/blog/2015/12/16/ismounted-antipattern.html
const makeCancelable = promise => {
  let hasCanceled_ = false;
   const wrappedPromise = new Promise((resolve, reject) => {
    promise.then(
      val => (hasCanceled_ ? reject({ isCanceled: true }) : resolve(val)),
      error => (hasCanceled_ ? reject({ isCanceled: true }) : reject(error))
    );
  });
   return {
    promise: wrappedPromise,
    cancel() {
      hasCanceled_ = true;
    }
  };
};