Elysia Route Generator

Elysia is a TypeScript-first web framework for Bun (and Node.js) focused on performance and developer experience. It provides end-to-end type safety using its treaty client, built-in schema validation via TypeBox (t.*), and a fluent route builder API. Elysia is known for being one of the fastest JavaScript web frameworks available.

Elysia uses TypeBox schemas (t.Object, t.String, t.Number, etc.) for request body, query parameters, and response types. These schemas are used both for runtime validation AND for generating TypeScript types automatically — eliminating the need to write types separately. The treaty client (Eden) then picks up these types for fully typed API calls.

Elysia's route methods mirror HTTP verbs: .get() for read operations, .post() for creating resources, .put() for full updates, .patch() for partial updates, .delete() for deletion. Each accepts a path string, a handler function, and an optional config object for body/query/params schemas and documentation metadata.

Elysia authentication is typically handled with plugins or derive/onBeforeHandle hooks. For Bearer token auth, add .onBeforeHandle(({ headers, set }) => { const token = headers.authorization?.split(' ')[1]; if (!token) { set.status = 401; return 'Unauthorized'; } }) as a guard. For reusable auth, create a plugin with new Elysia().derive({ as: 'scoped' }, () => ({ user })) and compose it.

Eden treaty is Elysia's type-safe client library. After defining your Elysia app, use treaty(app) on the client side to get a fully typed API client — autocomplete for routes, request bodies, and response types. This is Elysia's flagship feature: zero-effort end-to-end TypeScript without code generation or separate type definitions.

Use .onError({ code, error, set }) for global error handling, or throw new Error() with Elysia's built-in error classes like error('NOT_FOUND', 'Resource not found'). Elysia maps HTTP error codes automatically: error('NOT_FOUND') → 404, error('VALIDATION') → 422, error('UNAUTHORIZED') → 401. Add .error({ MyCustomError }) to register custom error types with proper status codes.