Middleware/Pipeline pattern

middlewares.js

const generator = () => {
  const middlewares = []

  const use = (fn) => middlewares.push(fn)

  const runMiddleware = index => {
    if (index < middlewares.length) {
      middlewares[index](() => runMiddleware(index + 1))
    }
  }

  const run = () => {
    runMiddleware(0)
    console.log('The end!')
  }

  return {
    run,
    use
  }
}

module.exports = generator