koajs/koa-roles

koa-roles is a tool for controlling who can access what in a web application built with Koa, a JavaScript framework for building web servers. It lets you define rules like "anonymous visitors can only see the home page" or "moderators can access private pages" and then automatically blocks anyone who doesn't meet the criteria. Think of it as a bouncer for your website that checks each visitor's permissions before letting them through to certain pages or actions. The way it works is straightforward. You create a Roles instance, attach it to your app, and then write a series of rules that run in order. Each rule checks the current user and the action they're trying to perform, returning true (allowed), false (denied), or nothing (let the next rule decide). If no rule grants access, the request is rejected with an error message. You can customize how denials are handled, for example, returning a JSON error for API clients or rendering an HTML "access denied" page for browser visitors. On individual routes, you tag them with permissions like user.can('access private page') so the framework knows which rule set to check. This would be useful for a founder or developer building a web app with multiple user types, say, a forum with anonymous readers, logged-in members, moderators, and admins. Instead of scattering permission checks throughout your code, you centralize the logic in one place. A PM building a dashboard app could use it to ensure only certain team members see billing pages or admin settings. The project is a Koa-specific adaptation of an earlier tool called connect-roles, built for the older Connect/Express ecosystem. It follows Koa's async style, using modern JavaScript features like async functions. The README doesn't go into deeper architectural detail beyond the usage example, but the code shown is clean and covers the main patterns you'd need.