根据月份算出当前月有多少天

//是否是闰年
    isLeapYear(year:number):any{
        if (((year % 4)==0) && ((year % 100)!=0) || ((year % 400)==0)) {
            return (true);
        } else { 
            return (false);
        }
    }

//根据年月得到天数
    getDayNumByYearMonth (year:number,month:number):any{
        let day=0;
        switch (month) {
            case 1:
                day=31;
                break;
            case 3:
                day=31;
                break;
            case 5:
                day=31;
                break;
            case 7:
                day=31;
                break;
            case 8:
                day=31;
                break;
            case 10:
                day=31;
                break;
            case 12:
                day=31;
                break;
            case 4:
                day=30;
                break;
            case 6:
                day=30;
                break;
            case 9:
                day=30;
                break;
            case 11:
                day=30;
                break;
            case 2:
                day=this.isLeapYear(year) ? 29 : 28;
                break;
        }
        return day;
    }