SOURCE

/*
 *@Description: 给一个数值截取指定位数（不足补0，超出四舍五入），并返回添加指定前缀的字符串
 *@params: currency 当前值
 *@params: pre 前缀
 *@params: precision 截取/补全位数
 *@Return: return 新字符串
 */
function currencyFormatter(currency, pre = '', precision = 2) {
  if (currency !== undefined && currency !== null) {
    currency = currency.toString().replace(/\$|,/g, '');
  }
  // 检查传入数值为数值类型
  if (isNaN(currency) || currency === '' || currency === null) {
    return '';
  }

  // 获取符号(正/负数)
  const sign = currency * 1 === (currency = Math.abs(currency));

  currency = Math.floor(currency * Math.pow(10, precision) + 0.50000000001); // 把指定的小数位先转换成整数.多余的小数位四舍五入
  let cents = currency % Math.pow(10, precision); // 求出小数位数值
  currency = Math.floor(currency / Math.pow(10, precision)).toString(); // 求出整数位数值

  if (precision !== 0) {
    cents = cents.toString(); // 把小数位转换成字符串,以便求小数位长度

    // 补足小数位到指定的位数
    while (cents.length < precision) {
      cents = '0' + cents;
    }
    cents = '.' + cents;
  } else {
    cents = '';
  }

  if (currency) {
    currency = thousandthFormatter(currency);
  }
  return pre + ((sign ? '' : '-') + currency + cents);
}
function thousandthFormatter(value) {
  let currency = value + '';
  let result = 0;
  if (currency) {
    // 对整数部分进行千分位格式化.
    for (let i = 0; i < Math.floor((currency.length - (1 + i)) / 3); i++) {
      currency =
        currency.substring(0, currency.length - (4 * i + 3)) +
        ',' +
        currency.substring(currency.length - (4 * i + 3));
    }
    result = currency;
  }
  return result;
}

console.log(currencyFormatter(-123.3089,'#',3))