Middleware

Middleware receives a mutable Context and returns a Response. Call ctx.next() to continue, or return a response to stop the chain.

Application middleware

import { App } from "limette";

export const app = new App().fsRoutes();
app.use(async (ctx) => {
  const response = await ctx.next();
  response.headers.set("x-app", "limette");
  return response;
});

app.use() runs for every request, including requests that will become 404 or 405 responses. Global middleware runs in registration order before a matched route. A matching app.all(path, handler) registered before the route can wrap it. Imperative routes may pass multiple handlers to a method such as app.get(path, first, second).

Filesystem middleware

Export handler from _middleware.ts in routes/ or a nested route directory:

// routes/admin/_middleware.ts
import type { Middleware } from "limette";

export const handler: Middleware = async (ctx) => {
  if (!ctx.request.headers.has("authorization")) {
    return new Response("Unauthorized", { status: 401 });
  }
  return ctx.next();
};

A filesystem route receives middleware from the route root down to its directory. handler may be one function or an array of functions; array members run in order. The request chain runs global middleware, previously registered matching all handlers, inherited filesystem middleware, then the route handler. Code after await ctx.next() runs on the way back out.

Use ctx.state for data shared within one request. See Context and state.