index.js

const {
  exec
} = require('child_process')

const fs = require('fs'),
  express = require('express'),
  app = express(),
  cors = require('cors')

app.options('/print/:printer/:id', cors())
app.post('/print/:printer/:id', cors(), (req, res) => {
  const userInfo = req.body.userInfo
  const text = `\n------\n> ${userInfo.nome}\n> ${userInfo.stanza} \n> ${userInfo.ristoro}\n-----\n`
  const printer = req.params.printer === '1' ? '-P Zebra-TLP2844' : ''

  fs.writeFile(`./text/${req.params.id}.txt`, text, function(err) {
    if (err) {
      return console.log(err)
    }
    exec(`lpr ${printer} ./text/${req.params.id}.txt`, (err, stdout, stderr) => {
      if (err) {
        // node couldn't execute the command
        return
      }
    })
  })
  res.send(req.params)
})

app.listen(3000, function() {
  console.log('Zebra Print Server running on port 3000!')
})