Node.js big5 / utf8 字串轉換

var Iconv  = require('iconv').Iconv;
var iconvToUtf8 = new Iconv('Big5', 'UTF8');
var encoded = "%A4%F4%AAd";
var decoded = urlDecodeBytes(encoded);
bufUtf8 = iconvToUtf8.convert(decoded);
console.log(bufUtf8);
console.log("bufUtf8 ", new String(bufUtf8, "UTF8"));
 
function urlDecodeBytes(encoded) {
  let decoded = Buffer.from('')
  for (let i = 0; i < encoded.length; i++) {
    if (encoded[i] === '%') {
      const charBuf = Buffer.from(`${encoded[i + 1]}${encoded[i + 2]}`, 'hex')
      decoded = Buffer.concat([decoded, charBuf])
      i += 2
    } else {
      const charBuf = Buffer.from(encoded[i])
      decoded = Buffer.concat([decoded, charBuf])
    }
  }
  return decoded
}
 
function isUrlSafe(char) {
  return /[a-zA-Z0-9\-_~.]+/.test(char)
}