CEX.IO private API auth in Google apps scripts (google sheet)

cex_private_api_auth.gs

function cex_auth(command, user_id, key, secret, callback) {
  var uri = "https://cex.io/api/";
  var nonce = new Date().getTime();

  var signature = Utilities.computeHmacSignature(Utilities.MacAlgorithm.HMAC_SHA_256, nonce.toString()+user_id+key, secret);
  var stringSignature = signature.map(function(byte) {
    return ('0' + (byte & 0xFF).toString(16)).slice(-2);
  }).join('').toUpperCase();
  
  var params = {
    "method": "post",
    "payload": {
      "key": key,
      "signature": stringSignature,
      "nonce": nonce.toString()
    }
  };
  
  var response = UrlFetchApp.fetch(uri+command, params);
  var dataAll = JSON.parse(response.getContentText());
  
  callback(dataAll);
}