Node Examples

// 1. HTTP server, no framework
import { createServer } from 'http';

const server = createServer(async (req, res) => {
  if (req.url === '/healthz') return res.end('ok');
  if (req.url === '/json') {
    res.writeHead(200, { 'content-type': 'application/json' });
    return res.end(JSON.stringify({ ts: Date.now() }));
  }
  res.writeHead(404); res.end('not found');
});

server.listen(3000, () => console.log('listening'));


// 2. Stream big files - no slurping
import { createReadStream, createWriteStream } from 'fs';
import { pipeline } from 'stream/promises';
import { createGzip } from 'zlib';

await pipeline(
  createReadStream('big.log'),
  createGzip(),
  createWriteStream('big.log.gz')
);


// 3. Spawn a child process - typed wrapper
import { spawn } from 'child_process';

function run(cmd: string, args: string[], opts = {}): Promise<{ stdout: string; stderr: string }> {
  return new Promise((resolve, reject) => {
    const p = spawn(cmd, args, opts);
    let stdout = '', stderr = '';
    p.stdout.on('data', (d) => stdout += d);
    p.stderr.on('data', (d) => stderr += d);
    p.on('close', (code) => code === 0 ? resolve({ stdout, stderr }) : reject(new Error(stderr)));
  });
}

const { stdout } = await run('git', ['rev-parse', 'HEAD']);


// 4. Scheduled job with node-cron
import cron from 'node-cron';
cron.schedule('*/5 * * * *', async () => {
  console.log('every 5 min', new Date().toISOString());
});


// 5. Env-driven config with zod
import { z } from 'zod';
const Env = z.object({
  PORT: z.coerce.number().default(3000),
  DATABASE_URL: z.string().url(),
  NODE_ENV: z.enum(['development', 'production', 'test']).default('development'),
});
export const env = Env.parse(process.env);


// 6. Worker thread for CPU work
// worker.ts
import { parentPort } from 'worker_threads';
parentPort?.on('message', (n: number) => parentPort?.postMessage(fib(n)));
function fib(n: number): number { return n < 2 ? n : fib(n - 1) + fib(n - 2); }

// main.ts
import { Worker } from 'worker_threads';
const w = new Worker(new URL('./worker.ts', import.meta.url));
w.on('message', (r) => console.log(r));
w.postMessage(40);


// 7. Graceful shutdown
process.on('SIGTERM', async () => {
  console.log('shutting down');
  await server.close();
  process.exit(0);
});

// Common Node snippets are in the lesson body.
console.log('Node examples');