Why isn't the POST (fetch) body coming?

Question

Web servers

Customer:

fetch('/chat', {
        method: 'POST',
        body: `INSERT INTO messages (textMessage, timeMessage, userName) VALUES ('hi', '2500-01-01' , 'Yana')`
    })

Server:

router.post('/',function(req,res,next){
  console.log('post!!!', req.body);
});

Server response:

post!!! {}

What's my mistake? Why doesn't the bodysuit come?

Answer 1

Problem solved like this.
Customer:

fetch('/chat', {
        headers: {body: `INSERT INTO messages (textMessage, timeMessage, userName) VALUES ('hi', '2500-01-01' , 'Yana')`},
        method: 'POST',
    })

Server:

router.post('/',function(req,res,next){
  console.log('post!!!', req.headers.body);
});

Is this the right decision? Can't figure out why this works and the previous one doesn't.