text: const JwtStrategy = require('passport-jwt').Strategy;
  const ExtractJwt = require('passport-jwt').ExtractJwt;
  const mongoose = require('mongoose');
  const User = mongoose.model('users');
  const keys = require('../config/keys');
  
  const opts = {};
  opts.jwtFromRequest = ExtractJwt.fromAuthHeaderAsBearerToken();
  opts.secretOrKey = keys.secretOrKey;
  
  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));
      }));
  };