JS 16进制字符串与字节数组的互转

function hexStringToByteArray(hexString) {
  if (hexString.length % 2 !== 0) {
    hexString = '0' + hexString;
  }
  const byteArray = [];
  for (let i = 0; i < hexString.length; i += 2) {
    const byte = parseInt(hexString.substr(i, 2), 16);
    byteArray.push(byte);
  }
  return byteArray;
}

function byteArrayToHexString(byteArray) {
  let hexString = '';
  for (let i = 0; i < byteArray.length; i++) {
    hexString += byteArray[i].toString(16).padStart(2, '0');
  }
  return hexString;
}

//字符串转字节序列
 function stringToByte(str) {
    var bytes = new Array();
    var len, c;
    len = str.length;
    for (var i = 0; i < len; i++) {
        c = str.charCodeAt(i);
        if (c >= 0x010000 && c <= 0x10FFFF) {
            bytes.push(((c >> 18) & 0x07) | 0xF0);
            bytes.push(((c >> 12) & 0x3F) | 0x80);
            bytes.push(((c >> 6) & 0x3F) | 0x80);
            bytes.push((c & 0x3F) | 0x80);
        } else if (c >= 0x000800 && c <= 0x00FFFF) {
            bytes.push(((c >> 12) & 0x0F) | 0xE0);
            bytes.push(((c >> 6) & 0x3F) | 0x80);
            bytes.push((c & 0x3F) | 0x80);
        } else if (c >= 0x000080 && c <= 0x0007FF) {
            bytes.push(((c >> 6) & 0x1F) | 0xC0);
            bytes.push((c & 0x3F) | 0x80);
        } else {
            bytes.push(c & 0xFF);
        }
    }
    return bytes;
    }
    //字节序列转ASCII码
//[0x24, 0x26, 0x28, 0x2A] ==> "$&C*"
 function byteToString(arr) {
    if (typeof arr === 'string') {
        return arr;
    }
    var str = '',
        _arr = arr;
    for (var i = 0; i < _arr.length; i++) {
        var one = _arr[i].toString(2),
            v = one.match(/^1+?(?=0)/);
        if (v && one.length == 8) {
            var bytesLength = v[0].length;
            var store = _arr[i].toString(2).slice(7 - bytesLength);
            for (var st = 1; st < bytesLength; st++) {
                store += _arr[st + i].toString(2).slice(2);
            }
            str += String.fromCharCode(parseInt(store, 2));
            i += bytesLength - 1;
        } else {
            str += String.fromCharCode(_arr[i]);
        }
    }
    return str;
    }