Generate SHA-256 HMAC in Base64 in Google AppScript

I would like to generate a base64 HMAC Authentication Code in Google Appscript.

This website - provides the exact solution: https://www.devglan.com/online-tools/hmac-sha256-online

I just somehow cant get it working natively in Google Appscript.

This is what I have at the moment - but its not giving me the right key:

function HMAC() {

var urlParam = "message";
var APIkey = 'secret';

  var hash = Utilities.computeHmacSha256Signature(urlParam, APIkey).reduce(function(str,chr){
    chr = (chr < 0 ? chr + 256 : chr).toString(16);
    return str + (chr.length==1?'0':'') + chr;
  },'');;

  Logger.log(Utilities.base64Encode(hash));
}

function HMAC() {
 var urlParam = "message";
 var APIkey = 'secret';

 // Compute HMAC-SHA256 hash
 var hash = Utilities.computeHmacSha256Signature(urlParam, APIkey,Utilities.Charset.UTF_8);

 // Convert byte array to Base64
 var base64Hash = Utilities.base64Encode(hash);

 // Log the Base64 encoded HMAC
 Logger.log(base64Hash);

 return base64Hash;
}

1. Byte Conversion: Utilities.computeHmacSha256Signature is given the message and the secret key. Here, Utilities.Charset.UTF_8 ensures that the string is encoded properly before the hash computation.

2. Base64 Encoding: Instead of converting the byte array to a hexadecimal string first, you directly encode it into Base64. This is done using Utilities.base64Encode, which correctly handles the byte array.