promexify

Safely use async await middlewares in express.

No need to write next() and deal with unresolved promise rejections.

Forget about writing this kind of middlewares...

async function myAsyncMiddleware (req, res, next) {
  try {
    await timeout(30)
    res.body = 'done'
    next()
  } catch (e) {
    next(e)
  }
}

usage

NOTE: Always use async functions. This will NOT work on functions retuning a Promise.

import express from 'express'
import { promexify } from 'promexify'

const timeout = ms => new Promise(resolve => setTimeout(() => resolve(), ms))

const app = express()
promexify(app) // <<< enables async await middlewares

app.use(
  async (req, res) => {
    await timeout(30) // some async call
    res.body = 'done'
  },
  async (err, req, res) => { // trap errors
    res.body = err.message
  },
  (req, res) => {
    res.end(res.body)
  },
)

also works on express.Router

const router = new express.Router()
promexify(router) // <<< enables async await middlewares

router.get('/',
  async (req, res) => {
    await timeout(30) // some async call
    res.body = 'done'
  }
)

const app = express()
app.use('/router', router)
app.use((req, res) => res.end(res.body))

Or even on a some middlewares

import express from 'express'
import { promex } from 'promexify'

const app = express()
app.use(
  bodyParser.json(),
  ...promex(
    async (req, res) { res.body = await () => {...} },
    async (req, res) { ... },
  )
)

license

MIT