代码如下：

<script language="JavaScript">

<!-- Begin
var today = new Date();
var now = today.getDate();
var year = today.getYear();
if (year < 2000) year += 1900; // Y2K fix
var month = today.getMonth();

var monarr = new Array(31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31);

// check for leap year
if (((year % 4 == 0) && (year % 100 != 0)) || (year % 400 == 0)) monarr[1] = "29";

// display day left
document.write("这个月还剩 " + (monarr[month]-now) + " 天了");
//  End -->
</script>