I searched many article for days i find they sending the token like this

res.json({token})

and using a middleware like this

function verifyToken(req, res, next){
  const authHeader = req.headers['authorization']
  const token = authHeader && authHeader.split(' ')[1]

  if (token == null) return res.sendStatus(401); // No token provided

  if(jwt.verify(token,process.env.JWT_SECRET)){
    next()
  }
}

How do they put that token in the req.headers['authorization']

when i console.log that it gives me only undefined

the res.json({token}) only send me to the token