Abort requests w/o event emitter

abort-request.js

const express = require('express')

const app = express()
const tokenTable = {}

const getMeaningOfLife = token => new Promise((resolve, reject) => {
  tokenTable[token] = () => {
    global.clearTimeout(handle)
    reject(new Error('aborted ' + token))
  }

  const handle = global.setTimeout(() => {
    resolve('42')
  }, 7500)
})

app.post('/abort/:token', (req, res) => {
  const { token } = req.params
  const reject = tokenTable[token]

  if (reject) {
    reject()
    res.end(token)
  } else {
    res.sendStatus(400)
    res.end('Unknown token: ' + token)
  }
})

app.get('/expensive-request', (req, res) => {
  const token = req.get('abort-token')

  if (!token || tokenTable[token]) {
    res.sendStatus(400)
    return res.end('Token not provided or already registered')
  }

  getMeaningOfLife(token)
    .then(mol => res.end(mol))
    .catch(err => res.end(err.message))
    .finally(() => {
      delete tokenTable[token]
    })
})

app.listen(3000)