thenifiedly

Promisifiedly call a callback style function/method with an es6 promise returned.

Install

$ npm install thenifiedly

Usage

import http from 'http'
import thenifiedly from 'thenifiedly'

const endRes = thenifiedly.callMethod.bind(null, 'end')

http.createServer(async (req, res) => {
  const githubRes = await thenifiedly.call(
    http.get,
    'https://github.com'
  )

  await thenifiedly.callMethod('write', res, `GitHub is ${
    githubRes.statusCode < 300 ? 'ok': 'down'
  }! `)

  await endRes(res, 'Bye!')
  console.log('Response Ended!')
})

This is especially useful when the function/instance to use comes from callback arguments or generated dynamically each time. So you don't need to wrap it every time before use, and might gain small performance enhancement from it. Check benchmark.

API

call: (fn[, ...args]) ⇒ Promise

Call a callback style function with postceding arguments, return a promise.

fn Function

The function to be called.

args any[]

Arguments to be passed to fn, except the most postceded callback.

async () => {
  const statOfMe = await thenifiedly.call(fs.stat, '/tmp/me')
}

callMethod: (method, instance[, ...args]) ⇒ Promise

method string|Symbol

The method name to be called on the instance object.

instance Object

The object contains the method to be called.

args any[]

Arguments to be passed to method, except the most postceded callback.

async () => {
  const worker = child_process.fork('some.js')
  await thenifiedly.callMethod('send', worker, { do: 'a job' })
}

tillEvent: (event, emitter) ⇒ Promise

Return a promise which resolves once the specified event fired by the emitter.

event string

The event name to be listened.

emitter EventEmitter

A node EventEmitter instance.

async () => {
  await thenifiedly.tillEvent('connect', db)
}

factory: (applier, options) ⇒ (...args) ⇒ Promise

Factory function to generate promisify helper for any kind of callback function.

applier: (callback, args) => void

Function to make arrange of the callback function applying.

callback: Function

Callback created by factory, you should inject it while calling.

args: any[]

Parameters passed to your generated helper function when using.

options Object

options.mutipleValues boolean

Whether multiple values passed to the callback, an array of values would be resolved instead if set to true. Default to false.

options.beginningError boolean

Whether callback arguments begins with the first arg as the error thrown. Default to true.

options.promiseClass boolean

The promise constructor to new the promise with. Default to native Promise.

function sumUntilEach(cb, ...nums) {
  cb(
    ...nums.reduce((arr, n) => {
      const len = arr.length
      const last = len === 0 ? 0 : arr[len - 1]
      return arr.concat(last + n)
    }, [])
  )
}

const thenified = factory(
  (cb, args) => {
    sumUntilEach(cb, ...args)
  }, {
    mutipleValues: true,
    beginningError: false,
    promiseClass: MyPromise,
  })

await thenified(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
// [1, 3, 6, 10, 15, 21, 28, 36, 45, 55]

Benchmark

Tested with node.js v10.8.0, check ./benchmarks for details.

### Test promisify function every time:
  util.promisify x 115,690 ops/sec ±2.69% (81 runs sampled)
  thenify x 226,758 ops/sec ±2.24% (82 runs sampled)
  es6-promisify x 1,433,982 ops/sec ±1.04% (80 runs sampled)
  pify x 1,969,359 ops/sec ±2.96% (77 runs sampled)
  thenifiedly.call x 3,704,139 ops/sec ±0.89% (84 runs sampled)

### Test promisify function once:
  util.promisify x 3,117,345 ops/sec ±0.86% (85 runs sampled)
  thenify x 3,529,109 ops/sec ±2.95% (83 runs sampled)
  es6-promisify x 1,559,947 ops/sec ±0.92% (83 runs sampled)
  pify x 3,164,405 ops/sec ±2.46% (82 runs sampled)
  thenifiedly.call x 3,724,577 ops/sec ±0.73% (83 runs sampled)

### Test promisify method every time:
  thenify-all x 204,321 ops/sec ±1.19% (82 runs sampled)
  pify x 1,494,615 ops/sec ±2.39% (82 runs sampled)
  thenifiedly.callMethod x 3,683,058 ops/sec ±0.75% (84 runs sampled)
  thenifiedly.callMethodFactory x 3,657,715 ops/sec ±2.42% (84 runs sampled)

### Test promisify method once:
  thenify-all x 3,591,625 ops/sec ±0.80% (86 runs sampled)
  pify x 3,628,348 ops/sec ±0.98% (80 runs sampled)
  thenifiedly.callMethod x 3,626,803 ops/sec ±2.34% (83 runs sampled)
  thenifiedly.callMethodFactory x 3,738,145 ops/sec ±0.98% (84 runs sampled)

License

MIT