金额格式化

function formatMoney(num, digits = 2) {
  return Number(num).toLocaleString("zh-CN", {
    minimumFractionDigits: digits,
    maximumFractionDigits: digits
  });
}

// Manual implementation
function formatMoney2(num) {
  const [int, dec] = String(num).split(".");
  return int.replace(/\B(?=(\d{3})+(?!\d))/g, ",") + (dec ? "." + dec : "");
}