实例化示例:
//年月联动
new YMDselect('year1','month1'); new YMDselect('year1','month1',1990); new YMDselect('year1','month1',1990,2);
//年月日联动
new YMDselect('year1','month1','day1'); new YMDselect('year1','month1','day1',1990); new YMDselect('year1','month1','day1',1990,2); new YMDselect('year1','month1','day1',1990,2,10);