LocalAuthenticationStrategy.js

passport.use(new LocalStrategy(function (username, password, done) {
    'use strict';

    var findUser = User.findOne({username: username}).exec();

    var verifyUserPassword = findUser.then(function(user){
        return new Promise(function(resolve, reject) {
            if (!user) {
                // Password can't match against a nonexistent user's password
                return resolve({isMatch:false, user:user});
            }
            user.verifyPassword(password, function (err, isMatch) {
                if (err) {
                    return reject(err);
                }
                resolve({isMatch:isMatch, user:user});
            });
        });
    }, function(err) {
        return done(err);
    });

    verifyUserPassword.then(function(results){
        return done(null, results.isMatch ? results.user : false)
    }, function(err){
        return done(err);
    });

}));