Installation

NextRush targets ES2022 and stable ESM throughout — there's no CommonJS build for any @nextrush/* package. Node 22 is the oldest LTS line where that target lands cleanly, so it's the floor every adapter and example assumes. NextRush declares "engines": { "node": ">=22.0.0" } in every published package. See the FAQ for the full reasoning.

NextRush publishes ESM only, with no CommonJS build to fall back to. That's why your package.json needs "type": "module" before anything runs — and it explains the one-line setup in the next section. Installing on Bun, Deno, or the edge instead? See Runtimes.

• nextrush is the meta-package — one install re-exports @nextrush/core, @nextrush/router, @nextrush/adapter-node, @nextrush/errors, and @nextrush/types. Nothing else to add.
• createApp() builds the application, createRouter() gives you a router to attach routes to, app.route('/', router) mounts it, and listen(app, 8080) starts the Node adapter.
• tsx runs the TypeScript entry directly — no separate compile pass.

ctx.json() sends JSON responses automatically, but reading an incoming JSON request body is not. To handle a POST (or any body-bearing request) you must add a body parser — otherwise ctx.body stays undefined and the body is silently ignored.

Install it, then register it before your routes:

pnpm add @nextrush/body-parser

import { createApp, createRouter, listen } from 'nextrush';
import { bodyParser } from '@nextrush/body-parser'; // combined: JSON + urlencoded

const app = createApp();
const router = createRouter();

app.use(bodyParser()); // ← parse incoming bodies before routes run

router.post('/tasks', (ctx) => {
  const body = ctx.body as { title?: string }; // ctx.body is typed unknown
  ctx.json({ saved: body.title });
});

app.route('/', router);
await listen(app, 8080);

Only need JSON, with tighter limits? Swap the combined parser for the single json parser — same shape: import, register, read.

import { createApp, createRouter, listen } from 'nextrush';
import { json } from '@nextrush/body-parser';

const app = createApp();
const router = createRouter();

app.use(json({ limit: '10mb', strict: true }));

router.post('/tasks', (ctx) => {
  const body = ctx.body as { title?: string };
  ctx.json({ saved: body.title });
});

app.route('/', router);
await listen(app, 8080);

bodyParser() skips bodyless methods (GET/HEAD/DELETE/OPTIONS), enforces a 1 MB default limit, and rejects invalid JSON with a 400. Full options: Body parser.

NextRush ships full type definitions. This tsconfig.json matches what the framework's own examples and CI run against:

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "strict": true,
    "esModuleInterop": true,
    "skipLibCheck": true,
    "types": ["node"],
    "outDir": "dist",
    "rootDir": "src"
  },
  "include": ["src"]
}

Only using class-based controllers? Add "experimentalDecorators": true and "emitDecoratorMetadata": true to compilerOptions if you import from nextrush/class — that entry point auto-imports reflect-metadata itself. See Class-based controllers.

Cause: package.json is missing "type": "module", so Node tries to load ESM output as CommonJS.

Fix: add "type": "module" — NextRush publishes no CommonJS build for any package to fall back to.

Cause: importing nextrush/class without experimentalDecorators / emitDecoratorMetadata enabled in tsconfig.json.

Fix: add both compiler options — the reflect-metadata import itself is already handled for you.