Express server returning an empty body from a post request

Question

I've been working on a project with express, and have a post request set up. However, it returns an empty body on the response, but it appears to be working otherwise. Here's the server:

const express = require('express');
const app = express();
const http = require('http').Server(app);
var bodyParser = require('body-parser'); 
app.use(bodyParser.urlencoded({ extended: true }));
app.use(bodyParser.json());
app.use(bodyParser.raw());

app.get('/', (req, res) => {
  res.sendFile(__dirname + '/index.html');
});

app.use("/public", express.static(__dirname + "/public"));

http.listen(8080, '0.0.0.0' , function() {
  console.log('listening on localhost:8080');
});

app.post('/form', (req, res) => {
    console.log(req.body);
    res.end('bla bla bla');
    // I've also tried res.json and res.send
});

And here's the client:

fetch("/form", {method: "POST", headers: {'Content-Type': 'application/json'}, body: JSON.stringify({bla: "bla"})}).then((thing) => {
    console.log(thing);
    console.log(thing.json());
    console.log(thing.body);
});

This seems like it should work, but instead it returns this object:

Response 
body: (...)
bodyUsed: true
headers: Headers {}
ok: true
redirected: false
status: 200
statusText: "OK"
type: "basic"
url: "http://localhost:8080/form"
[[Prototype]]: Response

I can't seem to find where the error lies, or even whether it's working and I just don't know how to get the data from it.

Answer 1

I've figured it out! It turns out that my code was working all along, it's just that I had messed up the fetch request. What I should have done client-side was:

fetch("/form", {method: "POST", headers: {'Content-Type': 'application/json'}, body: JSON.stringify({bla: "bla"})})
.then(res => res.json())
.then(data => console.log(data));

I was missing the second .then() and that was throwing it off.