javascript calendar

document.writeln('<div id=ggDateLayer style="position: absolute; width: 142; height: 166; z-index: 9998; display: none">');
document.writeln('<span id=tmpSelectYearLayer  style="z-index: 9999;position: absolute;top: 2; left: 18;display: none"></span>');
document.writeln('<span id=tmpSelectMonthLayer style="z-index: 9999;position: absolute;top: 2; left: 75;display: none"></span>');
document.writeln('<table width="100%" border=0 cellspacing=1 cellpadding=0 width=142 height=160 bgcolor=#808080 onselectstart="return false">');
document.writeln('  <tr><td width=142 height=23 bgcolor=#FFFFFF><table width="100%" border=0 cellspacing=1 cellpadding=0 width=140 height=23>');
document.writeln('      <tr align=center><td width=15 align=center bgcolor=#808080 style="font-size:12px;cursor: hand;color: #FFD700" ');
document.writeln('        onclick="ggPrevM()" title="上月" whatever=good><b whatever=good>&lt;</b>');
document.writeln('      </td><td width=15 align=center bgcolor=#808080 style="font-size:11px;cursor: hand;color: #FFD700" ');
document.writeln('        onclick="ggPrevY()" title="上年" whatever=good><b whatever=good>&lt;&lt;</b>');
document.writeln('        </td><td width=60 align=center style="font-size:11px;cursor:default" whatever=good>');
document.writeln('        <span whatever=good id=ggYearHead ></span>&nbsp;年&nbsp;<span');
document.writeln('         id=ggMonthHead whatever=good ></span>&nbsp;月</td>');
document.writeln('        <td width=15 bgcolor=#808080 align=center style="font-size:11px;cursor: hand;color: #FFD700" ');
document.writeln('         onclick="ggNextY()" title="下年" whatever=good><b whatever=good>&gt;&gt;</b></td>');
document.writeln('        <td width=15 bgcolor=#808080 align=center style="font-size:11px;cursor: hand;color: #FFD700" ');
document.writeln('         onclick="ggNextM()" title="下月" whatever=good><b whatever=good>&gt;</b></td></tr>');
document.writeln('    </table></td></tr>');
document.writeln('  <tr><td width=142 height=120>');
document.writeln('    <table width="100%" border=0 cellspacing=1 cellpadding=0 width=140 height=120 bgcolor=#FFFFFF>');
var n=0; for (j=0;j<5;j++){ document.writeln (' <tr align=center>'); for (i=0;i<7;i++){
document.writeln('<td width=20 height=20 id=ggDay'+n+' style="font-size:12px" whatever=good onclick=ggDayClick(this.innerText)></td>');n++;}
document.writeln('</tr>');}
document.writeln('      <tr align=center><td width=20 height=20 style="font-size:12px" id=ggDay35 whatever=good ');
document.writeln('         onclick=ggDayClick(this.innerText)></td>');
document.writeln('        <td width=20 height=20 style="font-size:12px" id=ggDay36 whatever=good onclick=ggDayClick(this.innerText)></td></tr>');
document.writeln('    </table></td></tr><tr><td>');
document.writeln('        <table width="100%" border=0 cellspacing=1 cellpadding=0 width=100% bgcolor=#FFFFFF>');
document.writeln('</tr></table></td></tr></table></div>');

//==================================================== WEB 页面显示部分 ======================================================
var outObject;
function setday(tt,obj) //主调函数
{
  var dads  = document.all.ggDateLayer.style;var th = tt;
  var ttop  = tt.offsetTop;     //TT控件的定位点高
  var thei  = tt.clientHeight;  //TT控件本身的高
  var tleft = tt.offsetLeft;    //TT控件的定位点宽
  var ttyp  = tt.type;          //TT控件的类型
  while (tt = tt.offsetParent){ttop+=tt.offsetTop; tleft+=tt.offsetLeft;}
  dads.top  = (ttyp=="image")? ttop+thei : ttop+thei+6;
  dads.left = tleft;
  outObject = (arguments.length == 1) ? th : obj;
  dads.display = '';
  event.returnValue=false;
}

var MonHead = new Array(12);               //定义阳历中每个月的最大天数
    MonHead[0] = 31; MonHead[1] = 28; MonHead[2] = 31; MonHead[3] = 30; MonHead[4]  = 31; MonHead[5]  = 30;
    MonHead[6] = 31; MonHead[7] = 31; MonHead[8] = 30; MonHead[9] = 31; MonHead[10] = 30; MonHead[11] = 31;

var ggTheYear=new Date().getFullYear(); //定义年的变量的初始值
var ggTheMonth=new Date().getMonth()+1; //定义月的变量的初始值
var ggWDay=new Array(37);               //定义写日期的数组

function document.onclick() //任意点击时关闭该控件
{
  with(window.event.srcElement)
  { if (tagName != "INPUT" && getAttribute("whatever")==null)
    document.all.ggDateLayer.style.display="none";
  }
}

function ggWriteHead(yy,mm)  //往 head 中写入当前的年与月
  { document.all.ggYearHead.innerText  = yy;
    document.all.ggMonthHead.innerText = mm;
  }

function tmpSelectYearInnerHTML(strYear) //年份的下拉框
{
  if (strYear.match(/\D/)!=null){alert("年份输入参数不是数字！");return;}
  var m = (strYear) ? strYear : new Date().getFullYear();
  if (m < 1000 || m > 9999) {alert("年份值不在 1000 到 9999 之间！");return;}
  var n = m - 10;
  if (n < 1000) n = 1000;
  if (n + 26 > 9999) n = 9974;
  var s = "<select whatever=good name=tmpSelectYear style='font-size: 12px' "
     s += "onblur='document.all.tmpSelectYearLayer.style.display=\"none\"' "
     s += "onchange='document.all.tmpSelectYearLayer.style.display=\"none\";"
     s += "ggTheYear = this.value; ggSetDay(ggTheYear,ggTheMonth)'>\r\n";
  var selectInnerHTML = s;
  for (var i = n; i < n + 26; i++)
  {
    if (i == m)
       {selectInnerHTML += "<option value='" + i + "' selected>" + i + "年" + "</option>\r\n";}
    else {selectInnerHTML += "<option value='" + i + "'>" + i + "年" + "</option>\r\n";}
  }
  selectInnerHTML += "</select>";
  document.all.tmpSelectYearLayer.style.display="";
  document.all.tmpSelectYearLayer.innerHTML = selectInnerHTML;
  document.all.tmpSelectYear.focus();
}

function tmpSelectMonthInnerHTML(strMonth) //月份的下拉框
{
  if (strMonth.match(/\D/)!=null){alert("月份输入参数不是数字！");return;}
  var m = (strMonth) ? strMonth : new Date().getMonth() + 1;
  var s = "<select whatever=good name=tmpSelectMonth style='font-size: 12px' "
     s += "onblur='document.all.tmpSelectMonthLayer.style.display=\"none\"' "
     s += "onchange='document.all.tmpSelectMonthLayer.style.display=\"none\";"
     s += "ggTheMonth = this.value; ggSetDay(ggTheYear,ggTheMonth)'>\r\n";
  var selectInnerHTML = s;
  for (var i = 1; i < 13; i++)
  {
    if (i == m)
       {selectInnerHTML += "<option value='"+i+"' selected>"+i+"月"+"</option>\r\n";}
    else {selectInnerHTML += "<option value='"+i+"'>"+i+"月"+"</option>\r\n";}
  }
  selectInnerHTML += "</select>";
  document.all.tmpSelectMonthLayer.style.display="";
  document.all.tmpSelectMonthLayer.innerHTML = selectInnerHTML;
  document.all.tmpSelectMonth.focus();
}

function closeLayer()               //这个层的关闭
  {
    document.all.ggDateLayer.style.display="none";
  }

function document.onkeydown()
  {
    if (window.event.keyCode==27)document.all.ggDateLayer.style.display="none";
  }

function isLeapYear(year){
   if(((year%4)==0)&&((year%100)!=0)||((year%400)==0)){
     return(true);
   }else{
   return(false);
   }
 }

function GetMonthCount(year,month)  //闰年二月为29天
  {
    var c=MonHead[month-1];if((month==2)&&isLeapYear(year)) c++;return c;
  }

function GetDOW(day,month,year)     //求某天的星期几
  {
    var dt=new Date(year,month-1,day).getDay()/7; return dt;
  }

function ggPrevY()  //上年
  {
    if(ggTheYear > 999 && ggTheYear <10000){ggTheYear--;}
    else{alert("年份超出范围（1000-9999）！");}
    ggSetDay(ggTheYear,ggTheMonth);
  }
function ggNextY()  //下年
  {
    if(ggTheYear > 999 && ggTheYear <10000){ggTheYear++;}
    else{alert("年份超出范围（1000-9999）！");}
    ggSetDay(ggTheYear,ggTheMonth);
  }
function ggToday()  //Today Button
  {
    ggTheYear = new Date().getFullYear();
    ggTheMonth = new Date().getMonth()+1;
    ggSetDay(ggTheYear,ggTheMonth);
  }
function ggPrevM()  //上月
  {
    if(ggTheMonth>1){ggTheMonth--}else{ggTheYear--;ggTheMonth=12;}
    ggSetDay(ggTheYear,ggTheMonth);
  }
function ggNextM()  //下月
  {
    if(ggTheMonth==12){ggTheYear++;ggTheMonth=1}else{ggTheMonth++}
    ggSetDay(ggTheYear,ggTheMonth);
  }

function ggSetDay(yy,mm)   //主要的写程序**********
{
  ggWriteHead(yy,mm);
  for (var i = 0; i < 37; i++){ggWDay[i]=""};  //将显示框的内容全部清空
  var day1 = 1,firstday = new Date(yy,mm-1,1).getDay();  //某月第一天的星期几
  for (var i = firstday; day1 < GetMonthCount(yy,mm)+1; i++){ggWDay[i]=day1;day1++;}
  for (var i = 0; i < 37; i++)
  { var da = eval("document.all.ggDay"+i)     //书写新的一个月的日期星期排列
    if (ggWDay[i]!="")
      { da.innerHTML = "<b>" + ggWDay[i] + "</b>";
        da.style.backgroundColor = (yy == new Date().getFullYear() &&
        mm == new Date().getMonth()+1 && ggWDay[i] == new Date().getDate()) ? "#C9F1FA" : "#FF9900";
        da.style.cursor="hand"
      }
    else{da.innerHTML="";da.style.backgroundColor="";da.style.cursor="default"}
  }
}
function ggDayClick(n)  //点击显示框选取日期，主输入函数*************
{
  var yy = ggTheYear;
  var mm = ggTheMonth;
  if (mm < 10){mm = "0" + mm;}
  if (outObject)
  {
    if (!n) {outObject.value=""; return;}
    if ( n < 10){n = "0" + n;}
    outObject.value= yy + "-" + mm + "-" + n ; //注：在这里你可以输出改成你想要的格式
    closeLayer();
  }
  else {closeLayer(); alert("您所要输出的控件对象并不存在！");}
}
ggSetDay(ggTheYear,ggTheMonth);


注:onfocus="setday(this)"