make-cancellable.js

const makeCancelable = (promise) => {
  let isCanceled = false

  const wrappedPromise = new Promise((resolve, reject) => {
    promise.then(
      val => isCanceled ? reject({ isCanceled: true }) : resolve(val), // eslint-disable-line prefer-promise-reject-errors
      error => isCanceled ? reject({ isCanceled: true }) : reject(error) // eslint-disable-line prefer-promise-reject-errors
    )
  })

  return {
    promise: wrappedPromise,
    cancel: () => {
      isCanceled = true
    },
    isCanceled
  }
}