金额千分位

    const thousands = (num, decimalNum = 0) => {
      // decimalNum：保留几位小数，默认0
      let tempArr = [];
      const res = [];
      tempArr = num.toFixed(decimalNum).toString().split(".");
      tempArr[0]
        .split("")
        .reverse()
        .map((item, i) => {
          if (i % 3 == 0 && i != 0) {
            res.push(",");
          }
          res.push(item);
        });
      const decimalPointBefore = res.reverse().join("");
      const decimalPointAfter = tempArr.length > 1 ? `.${tempArr[1]}` : "";
      
      return decimalPointBefore + decimalPointAfter;
    };
    
    console.log(thousands(123456.546457));    // 123,457
    console.log(thousands(123456.546457, 2)); // 123,456.55