async await waterfall sample

waterfall.js

const waterfall = async function (input, ...funcs) {
  const list = []

  for(let f of funcs)
    if(!list.length)
      list.push(await f(input))
    else
      list.push(await f(list.shift())
  
  return list.pop()
}

const upper = (_) => {
  return new Promise(res => {
    res(_.toUpperCase())
  })
}

const reverse = (_) => {
  return new Promise(res => {
    res(_.split('').reverse().join(''))
  })
}

const space = (_) => {
  return new Promise(res => {
    res(_.replace(/ {0,}/g,' '))
  })
}

waterfall("tpircsavaj", upper, reverse, space).then(console.log)

This is really cool, thanks!