formatPrice.js

function formatPrice(val, fixedDecimals, currencyCode) {
  var absVal = Math.abs(val),
    parts = absVal.toString().split('.'),
    res;
  parts[0] = parts[0].replace(/\B(?=(\d{3})+(?!\d))/g, ",");
  if (fixedDecimals) {
    parts[1] = absVal.toFixed(fixedDecimals).split('.')[1];
  }
  res = parts.join(".");
  return (val < 0 ? '-' : '') + (currencyCode || '') + res;
}