Why does the response from the server come 3 times?

Question

JavaScript

On the client, ajax is generated on pure js (without jQuery). On the server I process on express.js

app.use(bodyParser.json());
app.post('/name', (req, res) => {
  res.status(200);
});

I create a request on the client:

form.addEventListener('submit', event => {
      event.preventDefault();
      var xhr = new XMLHttpRequest();
      var json = JSON.stringify({
              name: document.querySelector('#name-reg').value,
              pass: document.querySelector('#pass-reg').value,
            });
      xhr.open('POST', '/name', true);
      xhr.setRequestHeader("Content-Type", "application/json");
      xhr.setRequestHeader("X-Requested-With", "XMLHttpRequest");
      xhr.send(json);

      xhr.onreadystatechange = () => {
        xhr.status === 200 ? console.log('Зарегистрирован') : console.log('не зарегистрирован');
      };
    });

And Everything works, but the response comes to the client 3 times. At the same time, everything is empty in the consoles, that is, no errors occur.

UPD: I will clarify that there is only one request in the network tab, but the message is displayed in the console three times.
What is the problem?

Answer 1

Because somewhere in the code you request it three times. See not only the browser console, but also the network connections tab. Better yet, install fiddler and check it out.