js判断当前年龄

computingTime(val) {
      let oldTime = new Date(val);
      let yearBirth = oldTime.getFullYear();
      let monthBirth = oldTime.getMonth() + 1;
      let dayBirth = oldTime.getDate();
      let nowDate = new Date();
      let monthNow = nowDate.getMonth() + 1;
      let dayNow = nowDate.getDate();
      let age = nowDate.getFullYear() - yearBirth;

      if (
        monthNow < monthBirth ||
        (monthNow == monthBirth && dayNow < dayBirth)
      ) {
        age--;
      }
      return age;
    }