function DaysInMonth(Y, M) {
    with (new Date(Y, M, 1, 12)) {
        setDate(0);
        return getDate();
    }
}
 
function datediff(date1, date2) {
	var y1 = date1.getFullYear(), m1 = date1.getMonth(), d1 = date1.getDate(),
	    y2 = date2.getFullYear(), m2 = date2.getMonth(), d2 = date2.getDate();
	if (d1 < d2) {
		m1--;
		d1 += DaysInMonth(y2, m2);
	}
	if (m1 < m2) {
		y1--;
		m1 += 12;
	}
	return [y1 - y2, m1 - m2, d1 - d2];
}
 
function calage(birthday, toDate) {
	var thisBirthday = new Date(birthday); //將生日的文字日期轉成Javascript的日期格式
	var calday = thisBirthday.getDate(); 
	var calmon = thisBirthday.getMonth()+1; 
	var calyear = thisBirthday.getFullYear();
	
	var dat = new Date(toDate);  //計算到什麼時候，如果不填日期就是到現在
	var curday = dat.getDate(); 
	var curmon = dat.getMonth()+1; 
	var curyear = dat.getFullYear(); 
	
	if(curday == "" || curmon=="" || curyear=="" || calday=="" || calmon=="" || calyear=="") {
		alert("please fill all the values and click go -");
	}else	{
		var curd = new Date(curyear,curmon-1,curday);
		var cald = new Date(calyear,calmon-1,calday);
		var diff =  Date.UTC(curyear,curmon,curday,0,0,0) - Date.UTC(calyear,calmon,calday,0,0,0);
		var dife = datediff(curd,cald);
		//alert(dife[0]+" years, "+dife[1]+" months, and "+dife[2]+" days");
		return dife[0];
	}
}