Last Router

An isomorphic file-system router for the last-act ecosystem. Zero build step, one HTTP server, signals over the wire.

API

const server = createServer({ port, base })
const { url } = await server.connect()

File-system routes

src/page.js              →  /
src/about/page.js        →  /about
src/[username]/page.js   →  /:username

Each folder can colocate an api.js. Its default export receives an ApiRequest with method, path, params, query, body, headers, and cookies, and returns (or yields) the body that gets passed to the matching page.js.

page.js

A plain function component. Receives { router, params, body }. Top-level body fields are Signal.State values, so read them with .get() and they will update reactively on the client. Use createElement from last-act:

import { createElement } from '@incremental-code/last-act';

export default function Profile({ params: { username }, body }) {
    return createElement('div', undefined,
        createElement('h1', undefined, `Profile for ${username}`),
        createElement('p', undefined, body.greeting.get()),
    );
}

api.js — plain or streaming

Return a value, or yield partial updates:

// one-shot
export default async function ({ params, headers }) {
    return {
        greeting: `Hello, ${params.username}!`,
        host: headers.host ?? 'unknown-host',
    };
}

// streaming — each yield is a partial body merge
export default async function* ({ params }) {
    yield { greeting: 'Loading...' };
    await fetchSlowly();
    yield { greeting: `Hello, ${params.username}!` };
}

On the server, the api is drained and the merged body is rendered to HTML. On the client, each yielded chunk arrives as an NDJSON line and updates the body signals reactively.

router

router.path           // current path (signal-backed)
router.push(path)     // history.pushState + navigate
router.replace(path)  // history.replaceState + navigate

On the server, push and replace throw a redirect that becomes a 302.

Built-in health route

createServer() always serves GET /health with 200 OK and a plain-text body of ok. This route is reserved for process health checks and is handled before file-system routing.

Demo

cd demo && node index.js

Visit http://localhost:3000.