Express HTTP Context Demo

package.json

{
  "name": "express-context",
  "version": "1.0.0",
  "description": "",
  "main": "server.js",
  "dependencies": {
    "express": "^4.17.1",
    "express-http-context": "^1.2.3",
    "request": "^2.88.0"
  },
  "devDependencies": {},
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node server.js"
  },
  "author": "",
  "license": "ISC"
}

server.js

const express = require('express')
const httpContext = require('express-http-context')

const UserService = require('./service-user')

const app = express()

app.use(httpContext.middleware)

app.get('/:id', (req, res) => {
  httpContext.set('id', req.params.id)

  UserService.getUser().then((result) => {
    res.json(result)
  })
})

app.listen(3000)

service-user.js

const httpContext = require('express-http-context')

function getRandomTimeout() {
  return 0
  return Math.floor(Math.random() * 5000)
}

function getUser() {
  const timeout = getRandomTimeout()

  return new Promise((resolve) => {
    setTimeout(() => {
      resolve({
        id: httpContext.get('id'),
        timeout,
        now: Date.now(),
      })
    }, timeout)
  })
}

module.exports = {
  getUser,
}

task.js

const request = require('request')

const startTime = Date.now()

function send(id) {
  return new Promise((resolve, reject) => {
    request({
      uri: 'http://127.0.0.1:3000/' + id,
      json: true
    }, (err, res, data) => {
      if (err) {
        reject(err)
        return
      }

      resolve(data)
    })
  })
}

let counter = 100000

console.log('TASK BEGIN')

while (counter) {
  counter--

  let i = Math.floor(Math.random() * counter) + ''

  send(i).then((data) => {
    if (data.id !== i) {
      const newError = new Error('WARNING')
      newError.npType = 666
      throw newError
    }

    // console.log('While Success', `Cost ${Date.now() - startTime}ms`, i)
  }).catch((err) => {
    if (1 || err.npType === 666) {
      console.log('While Error', `Cost ${Date.now() - startTime}ms`, err.npType)
    }
  })
}

console.log('TASK END', Date.now() - startTime)