const http = require('http');

const hostname = '127.0.0.1';
const port = 3000;

const server = http.createServer((req, res) => {
  res.statusCode = 200;
  res.setHeader('Content-Type', 'text/plain');
  res.end('Hello World\n');
});

server.listen(port, hostname, () => {
  console.log(`Server running at http://${hostname}:${port}/`);
});

ls | wc

const { Writable } = require('stream');

const outStream = new Writable({
  write(chunk, encoding, callback) {
    console.log(chunk.toString().toUpperCase());
    callback();
  }
});

process.stdin.pipe(outStream);

const { Readable } = require('stream'); 

const inStream = new Readable();
inStream.push('first chunk\n');
inStream.push('second chunk\n');
inStream.push(null);

setTimeout(() => {
    inStream.pipe(process.stdout);
}, 2000);

const { Duplex } = require('stream');

const inoutStream = new Duplex({
  write(chunk, encoding, callback) {
    console.log(chunk.toString().toUpperCase());
    callback();
  },

  read(size) {
  }
});

inoutStream.push('first chunk\n');
inoutStream.push('second chunk\n');
inoutStream.push(null);

process.stdin.pipe(inoutStream).pipe(process.stdout);

const { Transform } = require('stream');

const upperCaseTr = new Transform({
  transform(chunk, encoding, callback) {
    this.push(chunk.toString().toUpperCase());
    callback();
  }
});

process.stdin
  .pipe(upperCaseTr)
  .pipe(process.stdout);