Calendar control is available under FF2.0, ie6

/*********************************************************
*     How to use
*
*      As shown below, set the control to readonly
 *     <input type="text" style="border:1px solid #cccccc;" 
 *         size="15" onclick="fPopCalendar(event,this,this)" 
 *         onfocus="()" readonly="readonly" />
 *     
*     If the page is garbled, put the following definition items containing Chinese characters on the page
********************************************************/
var gMonths=new Array("January","February","March","April","May","June","July","August","September","October","November","December");
var WeekDay=new Array("day","one","two","three","four","five","six");
var strToday="Today";
var strYear="year";
var strMonth="month";
var strDay="Day";
var splitChar="-";
var startYear=2000;
var endYear=2050;
var dayTdHeight=12;
var dayTdTextSize=12;
var gcNotCurMonth="#E0E0E0";
var gcRestDay="#FF0000";
var gcWorkDay="#444444";
var gcWeekDay="#990099";
var gcMouseOver="#79D0FF";
var gcMouseOut="#F4F4F4";
var gcToday="#444444";
var gcTodayMouseOver="#6699FF";
var gcTodayMouseOut="#CCCCFF";
var gdCtrl=new Object();
var goSelectTag=new Array();
var gdCurDate=new Date();
var giYear=curYear=();
var giMonth=curMonth=()+1;
var giDay=curDay=();
function $(){var elements=new Array();for(var i=0;i<;i++) {var element=arguments[i];if(typeof(arguments[i])=='string'){element=(arguments[i]);}if(==1){return element;}(element);}return elements;}
=function(){var startLength=;for(var i=0;i<;i++){this[startLength+i]=arguments[i];}return ;}
=function(){return parseInt(this,16);}
=function(){return ()?"":(/\s/g,"");}
function checkColor(){var color_tmp=(arguments[0]+"").replace(/\s/g,"").toUpperCase();var model_tmp1=arguments[1].toUpperCase();var model_tmp2="rgb("+arguments[1].substring(1,3).HexToDec()+","+arguments[1].substring(1,3).HexToDec()+","+arguments[1].substring(5).HexToDec()+")";model_tmp2=model_tmp2.toUpperCase();if(color_tmp==model_tmp1 ||color_tmp==model_tmp2){return true;}return false;}
function $V(){return $(arguments[0]).value;}
function fPopCalendar(evt,popCtrl,dateCtrl){=true;gdCtrl=dateCtrl;var evtDate="";if(){evtDate=;}else{evtDate=;}var reg=/(^\d{4})\-([0-1]\d)\-([0-2]\d$)/;if((evtDate)){();giYear=RegExp.$1;giMonth=RegExp.$2;giDay=RegExp.$3;}fSetYearMon(giYear,giMonth);var point=fGetXY(popCtrl);with($("calendardiv").style){left=+"px";top=(++1)+"px";visibility='visible';zindex='99';position='absolute';}$("calendardiv").focus();}
function fSetDate(iYear,iMonth,iDay){var iMonthNew=new String(iMonth);var iDayNew=new String(iDay);if(<2){iMonthNew="0"+iMonthNew;}if(<2){iDayNew="0"+iDayNew;}=iYear+splitChar+iMonthNew+splitChar+iDayNew;fHideCalendar();}
function fHideCalendar(){$("calendardiv").="hidden";for(var i=0;i<;i++){goSelectTag[i].="visible";}=0;}
function fSetSelected(){var iOffset=0;var iYear=parseInt($("tbSelYear").value);var iMonth=parseInt($("tbSelMonth").value);var aCell=$("cellText"+arguments[0]);with(aCell){var iDay=parseInt(innerHTML);if(checkColor(,gcNotCurMonth)){iOffset=(innerHTML>10)?-1:1;}iMonth+=iOffset;if(iMonth<1){iYear--;iMonth=12;}else if(iMonth>12){iYear++;iMonth=1;}}fSetDate(iYear,iMonth,iDay);}
function Point(iX,iY){=iX;=iY;}
function fBuildCal(iYear,iMonth){var aMonth=new Array();for(var i=1;i<7;i++){aMonth[i]=new Array(i);}var dCalDate=new Date(iYear,iMonth-1,1);var iDayOfFirst=();var iDaysInMonth=new Date(iYear,iMonth,0).getDate();var iOffsetLast=new Date(iYear,iMonth-1,0).getDate()-iDayOfFirst+1;var iDate=1;var iNext=1;for(var d=0;d<7;d++){aMonth[1][d]=(d<iDayOfFirst)?(iOffsetLast+d)*(-1):iDate++;}for(var w=2;w<7;w++){for(var d=0;d<7;d++){aMonth[w][d]=(iDate<=iDaysInMonth)?iDate++:(iNext++)*(-1);}}return aMonth;}
function fDrawCal(iYear,iMonth,iCellHeight,iDateTextSize){var colorTD="background-color:"+gcMouseOut+";border-color:"+gcMouseOut+";";var styleTD="height:"+iCellHeight+"px;font-weight:bolder;font-size:"+iDateTextSize+"px;vertical-align:middle; text-align:center;";var dateCal="";dateCal+="<tr>";for(var i=0;i<7;i++){dateCal+="<td style='"+colorTD+styleTD+"color:"+gcWeekDay+";'>"+WeekDay[i]+"</td>";}dateCal+="</tr>";for(var w=1;w<7;w++){dateCal+="<tr>";for(var d=0;d<7;d++){var tmpid=w+""+d;dateCal+="<td style='"+styleTD+"cursor:pointer;' onclick='fSetSelected("+tmpid+")'>";dateCal+="<span id='cellText"+tmpid+"'></span>";dateCal+="</td>";}dateCal+="</tr>";}return dateCal;}
function fUpdateCal(iYear,iMonth){var myMonth=fBuildCal(iYear,iMonth);var i=0;for(var w=1;w<7;w++){for(var d=0;d<7;d++){with($("cellText"+w+""+d)){=gcMouseOut;=gcMouseOut;=function(){=gcMouseOver;};=function(){=gcMouseOut;};if(myMonth[w][d]<0){=gcNotCurMonth;innerHTML=(myMonth[w][d]);}else{=((d==0)||(d==6))?gcRestDay:gcWorkDay;innerHTML=myMonth[w][d];if(iYear==giYear && iMonth==giMonth && myMonth[w][d]==giDay){=gcMouseOver;=function(){=gcMouseOver;};=function(){=gcMouseOver;};}if(iYear==curYear && iMonth==curMonth && myMonth[w][d]==curDay){=gcToday;=gcTodayMouseOut;=function(){=gcTodayMouseOver;};=function(){=gcTodayMouseOut;};}}}}}}
function fCurrentDate(){return curYear+strYear+curMonth+strMonth+curDay+strDay;}
function fSetYearMon(iYear,iMon){$("tbSelMonth").options[iMon-1].selected=true;for(var i=0;i<$("tbSelYear").length;i++){if($("tbSelYear").options[i].value==iYear){$("tbSelYear").options[i].selected=true;}}fUpdateCal(iYear,iMon);}
function fPrevMonth(){var iMon=$("tbSelMonth").value;var iYear=$("tbSelYear").value;if(--iMon<1){iMon=12;iYear--;}fSetYearMon(iYear,iMon);}
function fNextMonth(){var iMon=$("tbSelMonth").value;var iYear=$("tbSelYear").value;if(++iMon>12){iMon=1;iYear++;}fSetYearMon(iYear,iMon);}
function fGetXY(aTag){var oTmp=aTag;var pt=new Point(0,0);do{+=;+=;oTmp=;}while(()!="BODY");return pt;}
function getDateDiv(){var noSelectForIE="";var noSelectForFireFox="";if(){noSelectForIE="onselectstart='return false;'";}else{noSelectForFireFox="-moz-user-select:none;";}var dateDiv="";dateDiv+="<div id='calendardiv' onclick='=true' "+noSelectForIE+" style='"+noSelectForFireFox+"position:absolute;z-index:99;visibility:hidden;border:1px solid #999999;'>";dateDiv+="<table style='border:0px; background-color:#E0E0E0;' cellpadding='1' cellspacing='1' >";dateDiv+="<tr>";dateDiv+="<td><input type='button' id='PrevMonth' value='&lt;' style='height:20px;width:20px;font-weight:bolder;' onclick='fPrevMonth()'>";dateDiv+="</td><td><select id='tbSelYear' style='border:1px solid;' onchange='fUpdateCal($V(\"tbSelYear\"),$V(\"tbSelMonth\"))'>";for(var i=startYear;i<endYear;i++){dateDiv+="<option value='"+i+"'>"+i+strYear+"</option>";}dateDiv+="</select></td><td>";dateDiv+="<select id='tbSelMonth' style='border:1px solid;' onchange='fUpdateCal($V(\"tbSelYear\"),$V(\"tbSelMonth\"))'>";for(var i=0;i<12;i++){dateDiv+="<option value='"+(i+1)+"'>"+gMonths[i]+"</option>";}dateDiv+="</select></td><td>";dateDiv+="<input type='button' id='NextMonth' value='&gt;' style='height:20px;width:20px;font-weight:bolder;' onclick='fNextMonth()'>";dateDiv+="</td>";dateDiv+="</tr><tr>";dateDiv+="<td align='center' colspan='4'>";dateDiv+="<div style='background-color:#cccccc'><table width='100%' border='0' cellpadding='3' cellspacing='1'>";dateDiv+=fDrawCal(giYear,giMonth,dayTdHeight,dayTdTextSize);dateDiv+="</table></div>";dateDiv+="</td>";dateDiv+="</tr><tr><td align='center' colspan='4' nowrap>";dateDiv+="<span style='cursor:pointer;font-weight:bolder;' onclick='fSetDate(curYear,curMonth,curDay)' onmouseover='=\""+gcMouseOver+"\"' onmouseout='=\"#000000\"'>"+strToday+":"+fCurrentDate()+"</span>";dateDiv+="</tr></tr>";dateDiv+="</table></div>";return dateDiv;}
with(document){onclick=fHideCalendar;write(getDateDiv());}
Calendar control.htm