old_contents: 
  var engine = require('engine.io')
  var client = require('engine.io-client')
  
  var cp = require('child_process')
  var path = require('path')
  
  
  module.exports = () => {
    var server = engine.listen(process.env.WS_PORT)
    server.on('connection', (browser) => {
      var elserver, electron
  
      browser.on('message', (data) => {
        var req = JSON.parse(data)
        console.log('ws-server', req)
  
        if (req.message === 'connect') {
          elserver = cp.spawn('electron', [process.env.EL_APP], {detached: true})
          elserver.stdout.on('data', (e) => {
            var output = e.toString().trim()
            console.log(output)
            if (/electron-server/.test(output)) {
              electron = client('ws://localhost:' + process.env.EL_PORT)
              electron.on('open', () => {
                browser.send(JSON.stringify({message: 'connected'}))
              })
              electron.on('message', (data) => {
                var req = JSON.parse(data)
                console.log(req)
                console.log('------------------')
                browser.send(JSON.stringify(req))
              })
              electron.on('close', () => {
                browser.send(JSON.stringify({message: 'disconnected'}))
              })
            }
          })
          elserver.stderr.on('data', (e) => console.log(e.toString().trim()))
        }
        else {
          electron.send(JSON.stringify(req))
        }
      })
    })
  
    console.log('ws-server-ready', process.env.WS_PORT, '!')
  }
  
new_contents: 
  var engine = require('engine.io')
  var client = require('engine.io-client')
  
  var cp = require('child_process')
  
  
  module.exports = () => {
    var server = engine.listen(process.env.WS_PORT)
    server.on('connection', (browser) => {
      var elserver, electron
  
      browser.on('message', (data) => {
        var req = JSON.parse(data)
        console.log('ws-server', req)
  
        if (req.message === 'connect') {
          elserver = cp.spawn('electron', [process.env.EL_APP], {detached: true})
          elserver.stdout.on('data', (e) => {
            var output = e.toString().trim()
            console.log(output)
            if (/electron-server/.test(output)) {
              electron = client('ws://localhost:' + process.env.EL_PORT)
              electron.on('open', () => {
                browser.send(JSON.stringify({message: 'connected'}))
              })
              electron.on('message', (data) => {
                var req = JSON.parse(data)
                console.log(req)
                console.log('------------------')
                browser.send(JSON.stringify(req))
              })
              electron.on('close', () => {
                browser.send(JSON.stringify({message: 'disconnected'}))
              })
            }
          })
          elserver.stderr.on('data', (e) => console.log(e.toString().trim()))
        }
        else {
          electron.send(JSON.stringify(req))
        }
      })
    })
  
    console.log('ws-server-ready', process.env.WS_PORT, '!')
  }
  
subject: Remove unused variable