In Postman of the 3 options available for content type select "X-www-form-urlencoded" and it should work.
Also to get rid of error message replace:
app.use(bodyParser.urlencoded())
With:
app.use(bodyParser.urlencoded({
extended: true
}));
See https://github.com/expressjs/body-parser
The 'body-parser' middleware only handles JSON and urlencoded data, not multipart
As @SujeetAgrahari mentioned, body-parser is now inbuilt with express.js.
Use app.use(express.json());
to implement it in recent versions for JSON bodies. For URL encoded bodies (the kind produced by HTTP form POSTs) use app.use(express.urlencoded());