Fetch bitstamp api using google sheets script

bitstamp.gs

function onOpen(e) {
  eval(UrlFetchApp.fetch('https://cdnjs.cloudflare.com/ajax/libs/jsSHA/2.3.1/sha256.js').getContentText());
  var key = '';
  var secret = '';
  var customer_id = '';
  var nonce = new Date().getTime().toString();
  var message = nonce + customer_id + key
  var shaObj = new jsSHA("SHA-256", "BYTES");
  shaObj.setHMACKey(secret, "BYTES");
  shaObj.update(message);
  var signature = shaObj.getHMAC("HEX").toString().toUpperCase();
  Logger.log(signature)
  var url = "https://www.bitstamp.net/api/v2/balance/";
  
  var formData = {
    "key": key,
    "signature": signature,
    "nonce": nonce
  };
  
  var options = {
    "method": "post",
    "muteHttpExceptions": true,
    "payload": formData
  };
  
  var response = UrlFetchApp.fetch(url, options);
  Logger.log(response);
  var data = JSON.parse(response.getContentText());
  // Write data to excel sheet 
  
  var sheet = SpreadsheetApp.getActiveSheet();
  sheet.appendRow([data.ltcusd_fee,data.usd_available]);
  
  Logger.log(data);
}