Google Sheets Macros (Google App Script) for getting currency of number cell

get_currency.js

CURRENCY_MAP = {
  '$': 'USD',
  '₽': 'RUB', // there is a missing character in editor font
  '€': 'EUR',
  '฿': 'THB'
}

function _formatToCurrency(formatString) {
  var currencyRegexp = /\[.*(.)\]/g;
  var currency = currencyRegexp.exec(formatString)[1];
  var currencyCode = CURRENCY_MAP[currency];
  
  if (currencyCode) {
    return currencyCode.toUpperCase();
  } else {
    return new Error('Unknown currency '+currency);
  }
}

function getCurrency(cellValue, cellRow, cellColumn) {
  var spreadsheet = SpreadsheetApp.getActiveSheet();
  if (!cellValue || !cellColumn || !cellRow || !spreadsheet) {
    return new Error('Missing arguments');
  }
  
  var cell = spreadsheet.getRange(cellRow, cellColumn);
  var cellNumberFormat = cell.getNumberFormat();
  var currencyCode = _formatToCurrency(cellNumberFormat);
  
  if (currencyCode instanceof Error) {
    Logger.log(currencyCode);
    return currencyCode;
  }
  
  return currencyCode;
}

Thank you! By the way, I also put comma instead of semicolon in formulas. Everything mixed up after js.