在标题栏上显示系统日期时间

script var clocktext;
var pagetitle = document.title;
function scroll()
{　
　  today = new Date(); 
　　sec = today.getSeconds();
    hr = today.getHours();
　　min = today.getMinutes();
    if (hr <= 9)
         hr = "0" + hr;
    if (min <= 9)
    min = "0" + min;
    if (sec <= 9) sec = "0" + sec;
    var clocktext = " 现在时间是: " + hr + ":" + min + ":" + sec; 
    clocktimer = setTimeout("scroll()", 1000); document.title = pagetitle + clocktext;
}
if (document.all)
scroll();