hfn - hot functions

hfn.once.js

const asyncOnce = (fn) => {
  const promise
  return (...args) => {
    if (!promise) {
      promise = fn.apply(null, args)
    }
    return promise
  }
}

const init = asyncOnce(() => {
  console.log('init')

  return new Promise((resolve, reject) => {
    global.setTimeout(() => {
      resolve(true)
    }, 1000)
  })
})

;(async () => {
  await Promise.all([init(), init()])
  console.log(await init())
})()