Включите это в свой код:
app.use(BodyParser.urlencoded({ extended: true }))
Полный пример:
const BodyParser = require('body-parser')
const Express = require('express')
const Http = require('http')
// App
let app = Express()
app.use(BodyParser.urlencoded({ extended: true }))
// Router
var router = Express.Router()
router.post('/', function(req, res) {
console.log('\nREQUEST RECEIVED!!')
console.log(req.body)
res.writeHead(200, {'Content-Type': 'text/xml' })
res.end()
})
app.use(router)
// Server
let server = Http.createServer(app)
server.listen( 3115, err => {
if (err) console.log( 'Error listening : ' + err )
else console.log('Listening...')
})