[ragnese]

I disagree. Enums are fine if they're string-only. It's only the numeric enums that cause the issues everyone complains about enums for. If there were a lint for making sure all enums are string-only, it would be the best solution, IMO.

AFAIK, your solution is (slightly) worse than an enum in several ways and better in none:

    export enum Role {
        CUSTOMER = 'customer',
        ADMIN = 'admin',
        SYSTEM = 'system',
        STAFF = 'staff',
    }

I think that implements everything yours does, but is easier to grok and fewer lines/declarations.