left-srad.js

function * dawejPadding(str, len, ch=' '){
  let current = str.length;

  while(current < len){
    yield ch;
    current++;
  }
  yield str;
}

const printuj = (subject) => {
  for(const c of subject){
    process.stdout.write(c);
  }
  process.stdout.write('\n')
}

const leftLepszyPad = (str, len, ch=' ')=>{
  const missing = len - str.length;

  return `${new Array(missing).fill(ch).join('')}${str}`
}

const DUZO = 400000000
// printuj(leftLepszyPad('kuku', 100000000, 'X'))
printuj(leftPad('kuku', DUZO, 'X'))
printuj(dawejPadding('kuku', DUZO, 'X'))