Basically the same thing in Node.coffee, just because:

    { Server } = require 'ws'
    { spawn } = require 'child_process'

    command = process.argv[2]
    args = process.argv[3..]

    wss = new Server port: 8080
    wss.on 'connection', (ws) ->
      ps = spawn command, args
      ps.stdout.on 'data', (data) -> ws.send data.toString()
      ws.on 'message', (data) -> ps.stdin.write data.toString()
      ws.on 'close', -> ps.kill()
      ps.on 'close', -> ws.close()

(Needs a bit more error handling)