Javascript implements date difference calculation

<SCRIPT LANGUAGE="JavaScript"> 
<!-- 
//说明:这里用了Math.ceil()函数,向上取整,即零头算一天,^_^ 
var strDate1 = "2003-06-17 03:03:40.0"; 
var strDate2 = "2004-09-18 12:03:12.0"; 
strDate1=strDate1.substring(0,strDate1.lastIndexOf(".")).replace(/-/g,"/"); 
strDate2=strDate2.substring(0,strDate2.lastIndexOf(".")).replace(/-/g,"/"); 
var date1 = Date.parse(strDate1); 
var date2 = Date.parse(strDate2); 
alert("strDate2与strDate1相差"+Math.ceil((date2-date1)/(24*60*60*1000))+"天") 
//--> 
</SCRIPT> 
 
<SCRIPT LANGUAGE="JavaScript"> 
<!-- 
 
var strDate1 = "2004-09-17 03:03:00.0"; 
var strDate2 = "2004-09-17 04:05:00.0"; 
strDate1=strDate1.substring(0,strDate1.lastIndexOf(".")).replace(/-/g,"/"); 
strDate2=strDate2.substring(0,strDate2.lastIndexOf(".")).replace(/-/g,"/"); 
var date1 = Date.parse(strDate1); 
var date2 = Date.parse(strDate2); 
alert("strDate2与strDate1相差"+(date2-date1)/(60*60*1000)+"小时") 
//--> 
</SCRIPT>