romellem

function utf16slice(str, start, end) {
  // UTF-16 code units - same as native
  return str.slice(start, end);
}

function utf8slice(str, start, end) {
  // UTF-8 bytes; slicing mid-codepoint yields U+FFFD
  const bytes = new TextEncoder().encode(str);
  return new TextDecoder().decode(bytes.slice(start, end));
}