Isomorphic Strings

export function isIsomorphic(s: string, t: string): boolean {
  if (s.length !== t.length) {
    return false;
  }
 
  const n = s.length;
  const sdict = new Map<string, string>();
  const tdict = new Map<string, string>();
  for (let i = 0; i < n; i++) {
    const [sc, tc] = [s[i], t[i]];
    if (sdict.has(sc) || tdict.has(tc)) {
      if (sdict.get(sc) !== tc || tdict.get(tc) !== sc) {
        return false;
      }
    } else {
      sdict.set(sc, tc);
      tdict.set(tc, sc);
    }
  }
  return true;
}