几个常用的日期函数

        /* -- 计算两个字符(yyyy-mm-dd)的日期相隔天数 -- */
function date_compare(asstartdate,asenddate){
 var mistart = date.parse(asstartdate.replace(/\-/g, '/'));
 var miend   = date.parse(asenddate.replace(/\-/g, '/'));
 return (miend-mistart)/(1000*24*3600);
}

      /*-- 判断一个字符串(yyyy-mm-dd)的日期是否正确 -- */
function date_istrue(asdate){
 var lsdate  = asdate + "";
 var lodate  = lsdate.split("-");
 if (lodate.length!=3) return false;
 var liyear  = parseint(lodate[0]);
 var limonth = parseint(lodate[1]);
 var liday   = parseint(lodate[2]);
 if ((lodate[0].length>4)||(lodate[1].length>2)||(lodate[2].length>2)) return false;
 if (isnan(liyear)||isnan(limonth)||isnan(liday)) return false;
 if ((liyear<1900)||(liyear>3000)) return false;
 if ((limonth>12)||(limonth<=0))   return false;
 if (date_getday(liyear,limonth)<liday) return false;
 return !isnan(date.utc(liyear,limonth,liday));
}

      /*-- 返回某年某月的天数-- */
function date_getday(aiyear,aimonth){
 var loday = [0,31,28,31,30,31,30,31,31,30,31,30,31];
 if (aiyear%4==0) loday[2] = 29;
 return loday[aimonth];
}