一个简单定义问题！请大家帮忙看看要怎么定义

<%@ page import ="java.util.*"%>
<%@ page import ="java.sql.*"%>
<%@ page contentType="text/html;charset=GB2312" %>
<html><head><title>获取系统时间</title> 
<script><!-- 
function tick(clock){ 
var hours,minutes,seconds,ap; 
var inthours,intminutes,intseconds; 
var today,timestring; 
today=new Date(); 
inthours=today.getHours();
intminutes=today.getMinutes(); 
intseconds=today.getSeconds(); 
if(inthours==0){ 
hours="12:"; 
ap="midnight"; 
}else if(inthours<12){ 
hours=inthours+":"; 
ap="A.M."; 
}else if(inthours==12){ 
hours=inthours+":"; 
ap="noon"; 
}else if(inthours=inthours-12){ 
hours=inthours+":"; 
ap="P.M."; 
} 
if(intminutes<10){ 
minutes="0"+intminutes+":"; 
}else{ 
minutes=intminutes+":"; 
} 
if(intseconds<10){ 
seconds="0"+intseconds+" "; 
}else{ 
seconds=intseconds+" "; 
} 
timestring=hours+minutes+seconds+ap; 
//var clock = document.all.clock;
clock.innerHTML=timestring; 
window.settimeout("tick(clock.id)",100); 
} 
window.onload=tick(); 
//--> 
</script> 
</head> 
<body> 
<h1>系统时间</h1> 
<div id="clock" align="center" style="font-size:36;color:#0000ff" 
onmouseover="this.style.cursor='hand'" 
onclick="alert('现在的时间是：'+'n'+timestring)"> 
  <script><!-- 
   tick(clock); 
  //--> 
  </script> <p>请单击获取系统时间</p> 
</div> 
</body> 
</html>