js處理金額返回爲兩位小數，無舍入誤差解決方法

handlePrice = (param = '') => {
  if (typeof param !== 'string' && typeof param !== 'number') {
    console.error('傳入參數只能爲字符串');
    return false;
  }
  if (param === '') return param;
  const val = `${param}`;
  const index = val.indexOf('.');
  const len = val.length;
  const dotNum = len - index - 1;
  if (index === -1) {
    return `${val}.00`;
  } else if (dotNum === 1) {
    return `${val}0`;
  } else if (dotNum > 2) {
    return val.slice(0, index + 3);
  }
  return val;
};