Sending data from a form with further processing by NodeJS?

Question

JavaScript

Good day!
I am writing my first project using:

• NodeJS
  
• gulp
  
• SASS
  
• Jade
  
• and more...
  

All the problems that were encountered were easily (and sometimes not very) googled.
Now I'm stuck on a point that many people will think is obvious, but I can't seem to resolve it. The point is this:
I want to transfer the data that the user enters (screenshot 1, p. 1,2,3) to the server and save it as a JSON file (screenshot 2, p. 2; screenshot 3).
When using the code (lines 7-22, screenshot 2), when you click on "Submit", "Hello world" is displayed on the opened page, and the selected buttons are displayed in the console (screenshot 2, p. 3, but without input values), which means , the code runs without errors. In addition, I would like to perform all actions on one port and using one server (without using the crutch that I have now; screenshot 2, item 4).
On the web, I found many tutorials on processing this data, but in all that I saw, something like This syntax is no longer suitable, because the current version of Express is 4. Tell me: 1) What is the best way to deal with routing? 2) Which Gulp plugin is suitable for these purposes? 3) How to read in addition to the values ​​of the selected buttons also the values ​​of input(text)? 4*) Bonus question: what if the compiler swears when using the ES6 syntax in the "serve.js" task file? (because of this, I had to change arrow-functions and interpolation for the old version of ES). Screenshot 1: Screenshot 2: Screenshot 3:
app.get("/some/route", function(req, res){...})

Answer 1

import express from 'express';
import bodyParser from 'body-parser';

const app = express();

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

app.get('/', (req, res) => {
  res.sendStatus(200);
});

app.post('/', (req, res) => {
  console.log(req.body);
  res.json({
    status: 200,
    message: 'Ok'
  });
});

const server = app.listen(config.listen, (error) => {
  if (error) {
    console.error(error);
    process.exit(1);
    return;
  }

  const { address, port } = server.address();

  console.log(`Listening ${address}:${port}`);
});