find-leading-zero-hash.js

const crypto = require('crypto');

let hash;
let index = 0;

function check() {
  const data = hash.read().toString('hex');

  hash.removeListener('readable', check);

  if (data.substr(0, 10) != '0000000000') {
    index++;

    return process.nextTick(main);
  }

  console.log(data);
  console.log(index);
}

function main() {
  hash = crypto.createHash('sha256');
  hash.on('readable', check);
  hash.write(index.toString());
  hash.end();
}

main();