Reorganize String (Js)

/**
 * @param {string} S
 * @return {string}
 */
const reorganizeString = (S) => {
  let counts = [];
  for (let i = 0; i < 26; i++) {
    counts[i] = 0;
  }
  for (let i = 0; i < S.length; i++) {
    counts[S.charAt(i).charCodeAt(0) - 'a'.charCodeAt(0)] += 100;
  }
  for (let i = 0; i < 26; i++) {
    counts[i] += i;
  }
  //Encoded counts[i] = 100*(actual count) + (i)
  counts.sort((a, b) => a - b);
  let t = 1;
  let ret = [];
  for (let i = 0; i < 26; i++) {
    const ch = String.fromCharCode('a'.charCodeAt(0) + (counts[i] % 100));
    let count = Math.floor(counts[i] / 100);
    if (count > Math.floor((S.length + 1) / 2))
      return '';
    while (count > 0) {
      if (t >= S.length)
        t = 0;
      ret[t] = ch;
      t += 2;
      count--;
    }
  }
  return ret.join('');
};

console.log(reorganizeString('aab'));
// 'aba'

Demo