passport.js

const JwtStrategy = require('passport-jwt').Strategy;
const ExtractJwt = require('passport-jwt').ExtractJwt;
const User = require("./models/User");
const secretJWT = "I love programming";

const opts = {};
opts.jwtFromRequest = ExtractJwt.fromAuthHeaderAsBearerToken();
opts.secretOrKey = secretJWT;

module.exports = passport => {
  passport.use(
    new JwtStrategy(opts, (jwt_payload, done) => {
      User.findById(jwt_payload.id)
        .then(user => {
          if (user) {
            return done(null, user);
          }
          return done(null, false);
        })
        .catch(err => console.log(err));
    })
  );
};