<html>
<head>
<title>年月日三下拉框联动</title>
<meta http-equiv='Content-Type' content='text/html; charset=gb2312'>
<meta name='author' content='oiea'>
<script language="JavaScript">
<!--
function initDate(year,month,day)
{
//每个月的初始天数
MonDays = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
//当前的年份
var y = new Date().getFullYear();
//当前的月份
var m = new Date().getMonth()+1; //javascript月份为0-11
//但前的天份
var d = new Date().getDate();
//以今年为准，向后2年，填充年份下拉框
for (var i = y; i < (y+2); i++)
{
year.options.add(new Option(i,i));
}
//选中今年
year.value=y;
//填充月份下拉框
for (var i = 1; i <= 12; i++)
{
month.options.add(new Option(i,i));
}
//选中当月
month.value = m;
//获得当月的初始化天数
var n = MonDays[m-1];
//如果为2月，天数加1
if (m == 2 && isLeapYear(year.options[year.selectedIndex].value))
n++;
//填充日期下拉框
createDay(n,day);
//选中当日
day.value = new Date().getDate();
}
function change(year,month,day) //年月变化，改变日
{
var y = year.options[year.selectedIndex].value;
var m = month.options[month.selectedIndex].value;
//if (m == "" ){ clearOptions(day); return;}
var n = MonDays[m - 1];
if ( m ==2 && isLeapYear(y))
{
n++;
}
createDay(n,day)
}
function createDay(n,day) //填充日期下拉框
{
//清空下拉框
clearOptions(day);
//几天，就写入几项
for(var i=1; i<=n; i++)
{
day.options.add(new Option(i,i));
}
}
function clearOptions(ctl)//删除下拉框中的所有选项
{
for(var i=ctl.options.length-1; i>=0; i--)
{
ctl.remove(i);
}
}
function isLeapYear(year)//判断是否闰年
{
return( year%4==0 || (year%100 ==0 && year%400 == 0));
}
//-->
</script>
</head>
<body onload="initDate(document.form1.select_year,document.form1.select_month,document.form1.select_day)">
<form name="form1">
<select name="select_year" onchange="change(this, document.form1.select_month, document.form1.select_day)"></select>year
<select name="select_month" onchange="change(document.form1.select_year, this,document.form1.select_day)"></select>month
<select name="select_day"></select>day
</form>
</body>
</html>
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