serial port node.js

I need to write a code for node.js that receives a "post request" (in this case a word String ), and pass this word forward to serial port. Then you receive from this serial port another word and put this word as answer for a "post request".

It should be a simple code, but I do not understand much about node.js and I have read a lot of information and tutorials, but I have not found exactly how to do what I need.

I need this to finalize my little application (I'm far from being a web programmer) and I can not find examples of these in the middle of so much information.

The most I could write was:

var express = require('express')

var app = express()

app.get('/notes', function(req, res) {
  res.json({
    notes: "World"
  })
})

app.listen(3000)



var bodyParser = require('body-parser')

app.use(bodyParser.json())
app.use(bodyParser.urlencoded({
  extended: false
}))

app.post('/notes', function(req, res) {
  if (!req.body.notes || typeof req.body.notes != "string") {
    res.status(400).send("400 Bad Request")
  }

  req.user.customData.notes = req.body.notes
  req.user.customData.save()
  res.status(200).end()
})

And I do not know how to modify this to work with serial port.