promises.js

// let's see if the same happens using a common resolved promise

let promised = 42.1
  // here we are promisify-ing the thenable
  const staticPromise = (async () => {
    return ++promised
  })()
  
  const asyncStatic = async () => {
    return staticPromise
  }

  const asyncAwaitStatic = async () => {
    return await staticPromise
  }
  
  const asyncAsyncStatic = async () => {
    return asyncStatic()
  }

console.log(staticPromise)

// expected to be true, they are ALL false
console.log(staticPromise === asyncStatic(), asyncStatic() === asyncStatic(), asyncStatic() === asyncAwaitStatic(), asyncStatic() === asyncAsyncStatic())

// this is the first call to then
console.log('staticPromise', staticPromise.then(console.log.bind(console, 'staticPromise')))

console.log('asyncStatic', asyncStatic().then(console.log.bind(console, 'asyncStatic')))
console.log('asyncAwaitStatic', asyncAwaitStatic().then(console.log.bind(console, 'asyncAwaitStatic')))
console.log('asyncAsyncStatic', asyncAsyncStatic().then(console.log.bind(console, 'asyncAsyncStatic')))

thenable.js

let called = 0
let started

// this is a thenable
const start = () => ({
  then (resolve, reject) {
    return resolve(++called) || 'resolved'
  }
})

// here we are promisify-ing the thenable
const asyncStart = async () => {
  return started
}

const asyncAwaitStart = async () => {
  return await started
}

const asyncAsyncStart = async () => {
  return asyncStart()
}

// expected functions here
console.log(start)
console.log(asyncStart)
console.log(asyncAsyncStart)
console.log(asyncAwaitStart)

// initialize the promise
started = start()

// assertion and promises
console.log(started)
// I'm expecting the second to be true, but it isn't
console.log(asyncStart === asyncStart, asyncStart() === asyncStart())
// I'm expecting this to be true, as we are wrapping the same thenable, but it isn't
console.log(asyncStart() === asyncAsyncStart())

// this is the first call to then
console.log('start', started.then(console.log.bind(console, 'start')))

// things is getting weird here: the started thenable is called everytime, meaning it is in common to everyone
console.log('asyncStart', asyncStart().then(console.log.bind(console, 'asyncStart')))
console.log('asyncAwaitStart', asyncAwaitStart().then(console.log.bind(console, 'asyncAwaitStart')))
console.log('asyncAsyncStart', asyncAsyncStart().then(console.log.bind(console, 'asyncAsyncStart')))