How is correctly way to send firebase auth tokenId between front-end and node.js backend

I am during create a chat-app. I want to find a good way to safely connect front and backend using a TokenId from firebase auth.

1. Do I have to in every request from my front to backend send a TokenId?
2. It is possible to do it in session or something like that I can send token once and verified it once time too?

My current road.

My code front end where I send a token:

fetch('http://localhost:5500/check', {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
    },
    body: JSON.stringify({ token: token }),
  })
    .then(data => data.json())
    .then(e => console.log(e))
    .catch(err => console.log(err));
});

I get token on front end like that:

firebase.auth().currentUser.getIdToken(true)

My code backend verify token:

router.post('/check', urlencodedParser, (req, res) => {
  const {token} = req.body;

  admin
    .auth()
    .verifyIdToken(token)
    .then(function (decodedToken) {
      // let uid = decodedToken.uid;
      res.setHeader('Content-Type', 'application/json');
      res.send({status: 'Ok'});
    })
    .catch(function (error) {
      console.log(error);
      res.setHeader('Content-Type', 'application/json');
      res.send({status: 'err'});
    });
});