I'm Doing Promises Better, But Still Kind Of Wrong... One More Thing To Clear Up

I asked a question about JS Promises in this post: I'm doing Promises wrong... What am I missing here? And came up with something that help me overcome the issue I was having, but

Solution 1:

Your problem is that you missed to return the Promise.reject(…)s from your callbacks. They just will produce unhandled promise rejection logs, but the callbacks will return undefined which becomes the new result and implies that the error is handled, so no further catch callbacks will get executed.

However, that code should be simplified a lot anyway. Regarding the closing of the database connection, you should have a look at the disposer pattern or a finally method.

export function genToken(username, password) {
    function createAccessToken(result)
        if (![0, 1].includes(result.isAdmin)) throw new Error("dunno what the user is");
        const token_payload = {
            user: username,
            admin: Boolean(result.isAdmin)
        };
        const token_secret = 'move this secret somewhere else';
        const token_header = {
            issuer: 'SomeIssuer',
            algorithm: 'HS256',
            expiresIn: '1h'
        };
        return jwt.sign(token_payload, token_secret, token_header);
    }

    return db.open()
    .then(() => dbUserLevel('user'))
    .then(() => db.collection('users').findOne({ username: username, password: password }))
    .then(result => ({access_token: createAccessToken(result)}))
    .then(token => {
        db.close();
        return token;
    }, err => {
        db.close();
        throw err;
    });
}