// Detect character encoding and validate Base64
function detectCharset(input) {
  // Check if valid Base64
  const isBase64 = /^[A-Za-z0-9+/]*={0,2}$/.test(input.trim());

  // Detect encoding
  const hasNonAscii = /[^\x00-\x7F]/.test(input);
  let encoding = hasNonAscii ? 'UTF-8' : 'ASCII';

  // Character and byte count
  const charCount = input.length;
  const byteCount = new Blob([input]).size;

  // Detect line breaks
  const hasCRLF = /\r\n/.test(input);
  const hasLF = /(?<!\r)\n/.test(input);
  const lineBreakType = hasCRLF ? 'CRLF' : hasLF ? 'LF' : 'None';

  // Check UTF-8 validity
  const isValidUtf8 = (() => {
    try {
      const encoded = new TextEncoder().encode(input);
      const decoded = new TextDecoder('utf-8', { fatal: true }).decode(encoded);
      return decoded === input;
    } catch {
      return false;
    }
  })();

  return {
    isBase64,
    encoding,
    charCount,
    byteCount,
    lineBreakType,
    isValidUtf8
  };
}

// Example usage
const text = "Hello, 世界! 🌍";
const result = detectCharset(text);
console.log(result);
// Output: { isBase64: false, encoding: 'UTF-8', charCount: 13, byteCount: 19, ... }