日期和星期联动

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<title>新建网页 2</title>
<script>
function a(){
var curdate=new Date();
document.all.date1.value=curdate.getFullYear()+"-"+(curdate.getMonth()+1)+"-"+curdate.getDate();
document.all.week.value=curdate.getDay();
}
function b(){
var dateStr="2007-7-24";
var dateArr=dateStr.split("-");
var nextDate=new Date(dateArr[0],dateArr[1]-1,dateArr[2]);
document.all.date1.value=nextDate.getFullYear()+"-"+(nextDate.getMonth()+1)+"-"+nextDate.getDate();
document.all.week.value=nextDate.getDay();
}
function c(){
var dateStr=document.all.date1.value;
var dateArr=dateStr.split("-");
var nextDate=new Date(dateArr[0],dateArr[1]-1,dateArr[2]);
document.all.date1.value=nextDate.getFullYear()+"-"+(nextDate.getMonth()+1)+"-"+nextDate.getDate();
document.all.week.value=nextDate.getDay();
}
</script>
</head>
<body onload="a()">
日期:<input type=text id=date1 value="" onchange="c()">
星期:<input type=text id=week value="">
<input type=button onclick="b()" value="下一天">
</body>
</html>