see what async functions return when returning early, and after an await

async-early-return.js

'use strict'

async function delay (ms) {
  return new Promise((resolve, reject) => setTimeout(resolve, ms))
}

async function foo (returnEarly) {
  if (returnEarly) return new Date()

  await delay(1000)
  return new Date()
}

const TRACE = process.env.TRACE != null

async function main () {
  if (TRACE) console.trace(1); console.log('foo(true):       ', foo(true))
  if (TRACE) console.trace(2); console.log('await foo(true): ', await foo(true))
  if (TRACE) console.trace(3); console.log('foo(false):      ', foo(false))
  if (TRACE) console.trace(4); console.log('await foo(false):', await foo(false))
  if (TRACE) console.trace(5)

  // prints:
  //   foo(true):        Promise { 2018-07-03T18:14:54.014Z }
  //   await foo(true):  2018-07-03T18:14:54.017Z
  //   foo(false):       Promise { <pending> }
  //   await foo(false): 2018-07-03T18:14:55.021Z
}

main()