unix yes command in node.js

yes.js

// throughput is usually ~350-400 MiB/s
// run: node yes.js | pv > /dev/null

const buf = Buffer.alloc(4096, 'y\n', 'utf8');
const str = buf.toString();
const { Readable } = require('stream');

class Y extends Readable {
  _read() {
    this.push(str);
  }
}

const stream = new Y();

stream.pipe(process.stdout);



//---------------------------

// Averages 2.25 GiB/s
// Based on https://www.reddit.com/r/unix/comments/6gxduc/how_is_gnu_yes_so_fast/diuibhe/

const BUFSIZ = process.stdout._writableState.highWaterMark / 2;
const str = process.argv[2] || 'y';
const len = str.length + 1;
const buffer = Buffer.from(Array.from({ length: BUFSIZ }, () => str).join('\n'));

function yes() {
  // write accepts a callback function. while(true) will cause OOM crash
  // so this is recursive
  process.stdout.write(buffer, yes);
}

yes();