云南昆明火车站3.1:如何设定网页在特定的时间弹出一个对话框？

脚本啊，很容易实现的

<SCRIPT language=javascript>
<!--
calendar = new Date();
day = calendar.getDay();
month = calendar.getMonth();
date = calendar.getDate();
year = calendar.getYear();
if (year< 100) year = 1900 + year;
cent = parseInt(year/100);
g = year % 19;
k = parseInt((cent - 17)/25);
i = (cent - parseInt(cent/4) - parseInt((cent - k)/3) + 19*g + 15) % 30;
i = i - parseInt(i/28)*(1 - parseInt(i/28)*parseInt(29/(i+1))*parseInt((21-g)/11));
j = (year + parseInt(year/4) + i + 2 - cent + parseInt(cent/4)) % 7;
l = i - j;
emonth = 3 + parseInt((l + 40)/44);
edate = l + 28 - 31*parseInt((emonth/4));
emonth--;
var dayname = new Array ("星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六");
var monthname =
new Array ("1月","2月","3月","4月","5月","6月","7月","8月","9月","10月","11月","12月" );
document.write("<font color=FF0000>"+year +"年");
document.write(monthname[month]);
document.write(date + "日");
document.write(dayname[day]+" "+"</font>");

// January(1月份节日，以下同。)
if ((month == 0) && (date == 1)) document.write("元旦");
if ((month == 0) && (date == 10)) document.write("我的生日");
if ((month == 4) && (date == 1)) document.write("国际劳动节");
if ((month == 4) && (date == 4)) document.write("青年节");
if ((month == 5) && (date == 1)) document.write("国际儿童节");
if ((month == 11) && (date == 25)) document.write("圣诞节");

document.write("<br></font>");

//-->
</SCRIPT>