data-fetcher.js

const createDataFetcher = (url) => {
  let result = null
  let promise = null

  return () => {
    if (result != null) {
      return result;
    }

    if (promise === null) {
      promise = fetch(url).then(value => {
        result = value
      })
    }

    throw promise
  }
}

const fetchUser = createDataFetcher('http://website.com/users/me')