Javascript Middleware Pattern

nextify.js

function nextify (middlewares, callback) {
  return (...args) => {
    middlewares.slice(0).reverse().reduce((next, fn) => {
      return () => fn(...args, (err) => {
        if (err) {
          return callback(err)
        }

        next()
      })
    }, callback)()
  }
}

/** Usage */

const next = nextify([
  (a, b, next) => {console.log('CP1', a, b); next()},
  (a, b, next) => {console.log('CP2', a, b); next(new Error('fake error'))},
  (a, b, next) => {console.log('CP3', a, b); next()},
], (err) => console.log('DONE', {err}))

next('A', 'B')

/** Output */

// CP1 A B
// CP2 A B
// DONE { err:
//    Error: fake error
//        at nextify (/home/steven/code/nextify.js:17:51)
//        at /home/steven/code/nextify.js:4:20
//        at fn (/home/steven/code/nextify.js:9:9)
//        at nextify (/home/steven/code/nextify.js:16:46)
//        at /home/steven/code/nextify.js:4:20
//        at /home/steven/code/nextify.js:11:17
//        at Object.<anonymous> (/home/steven/code/nextify.js:21:1)
//        at Module._compile (module.js:571:32)
//        at Object.Module._extensions..js (module.js:580:10)
//        at Module.load (module.js:488:32) }