create-new-app/modules/isOnline.js

Easily generate a new React application, optionally with Express & MongoDB.

/*
  This module checks if the user is online.
  If it takes more than 3.5s (you can change that), it will assume a
  bad connection and the process will proceed as if the user is offline.

  Alternative packages:
    * http://bit.ly/2YZBWQA - `is-online`
    * http://bit.ly/2Z4uNhY - `is-reachable`
    * http://bit.ly/2YXGEyu - `connectivity`
*/

const dns = require('dns')

module.exports = (time = 3500) =>
  new Promise(resolve => {
    let slow = false

    // Prevent this from taking forever for slow connections.
    const tooSlow = setTimeout(() => {
      slow = true
      console.log('\nYour internet connection appears to be unstable.')
      console.log('Proceeding with offline mode...\n')
      resolve(false)
    }, time)

    /*
    https://nodejs.org/api/dns.html
    Use `.resolve` over `.lookup` since the former will always perform a network request.
  */
    dns.resolve('google.com', (err, records) => {
      clearTimeout(tooSlow)
      !slow && resolve(!err)
    })
  })