document.getElementById("id_name") has no properties
<head>
<script>
function getWeek(year, month, day)
{
var d1 = new Date(year, 0, 1);
var d2 = new Date(year, month-1, day, 1);
var dayMs = 24*60*60*1000; //一天毫秒数
var firstDay = (7-d1.getDay())*dayMs;
var weekMs = 7*dayMs; //一周毫秒数
d1 = d1.getTime();
d2 = d2.getTime();
return Math.ceil((d2-d1-firstDay)/weekMs)+1;
}
var now = new Date();
var weeknum = getWeek(now.getYear(), now.getMonth()+1, now.getDate()); //注意Date对象的getMonth()方法
document.getElementById("currweek").value = weeknum; //这里!!
</script>
<body>
<form name="logindata" action="sth.php" method="post">
<input type="hidden" name="currweek" id="currweek" value="0" /> //这里!!
</form>
...
</body>
</html>
提示:document.getElementById("id_name") has no properties