utils.js

const jwt = require('jsonwebtoken');

module.exports = {
    validateToken: (req, res, next) =>{
      const authorizationHeader = req.headers.authorization; 
      let result; 
      if (authorizationHeader){
          const token = req.headers.authorization.split(' ')[1]; // Bearer <token>
          const options = {
              expiresIn: '2d', 
              issuer: 'localhost:3000'
          };
          try {
              // verify makes sure that the token hasn't expired and has been issued by us
            result = jwt.verify(token, process.env.JWT_SECRET, options);

             // Let's pass back the decoded token to the request object
             req.decoded = result; 
             //we call next to pass execution to the subsequent middleware
             next();
          }catch (err){
              throw new Error(err);
          }
      }else{
        result = {
            error: 'Authentication error. Token required.',
            status: 401
        };  
        res.status(401).send(result);
      }
    }
};