<script language="javascript">
function setid()
{ var year=window.myform.page.value;
if((year%4==0&&year%100!=0)||(year%400==0))
{
document.write(year+"是闰年");
}
else{
document.write(year+"不是闰年");
}
}
</script>
<form name="myform" action="?" method="get">
<input type="text" name="page">
<input type="submit" value="Go" class="bl" onClick="setid();">
</form>