I read through the code and I think this is what you are asking about...
// Simple method to interface popup calendar with a text-entry box
function CP_select(inputobj, linkname, format) {
var selectedDate=(arguments.length>3)?arguments[3]:null;
if (!window.getDateFromFormat) {
alert("calendar.select: To use this method you must also include 'date.js' for date formatting");
return;
}
if (this.displayType!="date"&&this.displayType!="week-end") {
alert("calendar.select: This function can only be used with displayType 'date' or 'week-end'");
return;
}
if (inputobj.type!="text" && inputobj.type!="hidden" && inputobj.type!="textarea") {
alert("calendar.select: Input object passed is not a valid form input object");
window.CP_targetInput=null;
return;
}
if (inputobj.disabled) { return; } // Can't use calendar input on disabled form input!
window.CP_targetInput = inputobj;
window.CP_calendarObject = this;
this.currentDate=null;
var time=0;
if (selectedDate!=null) {
time = getDateFromFormat(selectedDate,format)
}
else if (inputobj.value!="") {
time = getDateFromFormat(inputobj.value,format);
}
if (selectedDate!=null || inputobj.value!="") {
if (time==0) { this.currentDate=null; }
else { this.currentDate=new Date(time); }
}
window.CP_dateFormat = format;
this.showCalendar(linkname);
}
// Return a string containing all the calendar code to be displayed
function CP_getCalendar() {
var now = new Date();
// Reference to window
if (this.type == "WINDOW") { var windowref = "window.opener."; }
else { var windowref = ""; }
var result = "";
// If POPUP, write entire HTML document
if (this.type == "WINDOW") {
result += "<HTML><HEAD><TITLE>Calendar</TITLE>"+this.getStyles()+"</HEAD><BODY MARGINWIDTH=0 MARGINHEIGHT=0 TOPMARGIN=0 RIGHTMARGIN=0 LEFTMARGIN=0>\n";
result += '<CENTER><TABLE WIDTH=100% BORDER=0 BORDERWIDTH=0 CELLSPACING=0 CELLPADDING=0>\n';
}
else {
result += '<TABLE CLASS="'+this.cssPrefix+'cpBorder" WIDTH=144 BORDER=1 BORDERWIDTH=1 CELLSPACING=0 CELLPADDING=1>\n';
result += '<TR><TD ALIGN=CENTER>\n';
result += '<CENTER>\n';
}
// Code for DATE display (default)
// -------------------------------
if (this.displayType=="date" || this.displayType=="week-end") {
if (this.currentDate==null) { this.currentDate = now; }
if (arguments.length > 0) { var month = arguments[0]; }
else { var month = this.currentDate.getMonth()+1; }
if (arguments.length > 1 && arguments[1]>0 && arguments[1]-0==arguments[1]) { var year = arguments[1]; }
else { var year = this.currentDate.getFullYear(); }
var daysinmonth= new Array(0,31,28,31,30,31,30,31,31,30,31,30,31);
if ( ( (year%4 == 0)&&(year%100 != 0) ) || (year%400 == 0) ) {
daysinmonth[2] = 29;
}
var current_month = new Date(year,month-1,1);
var display_year = year;
var display_month = month;
var display_date = 1;
var weekday= current_month.getDay();
var offset = 0;
offset = (weekday >= this.weekStartDay) ? weekday-this.weekStartDay : 7-this.weekStartDay+weekday ;
if (offset > 0) {
display_month--;
if (display_month < 1) { display_month = 12; display_year--; }
display_date = daysinmonth[display_month]-offset+1;
}
var next_month = month+1;
var next_month_year = year;
if (next_month > 12) { next_month=1; next_month_year++; }
var last_month = month-1;
var last_month_year = year;
if (last_month < 1) { last_month=12; last_month_year--; }
var date_class;
if (this.type!="WINDOW") {
result += "<TABLE WIDTH=144 BORDER=0 BORDERWIDTH=0 CELLSPACING=0 CELLPADDING=0>";
}
result += '<TR>\n';
var refresh = windowref+'CP_refreshCalendar';
var refreshLink = 'javascript:' + refresh;
if (this.isShowNavigationDropdowns) {
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="78" COLSPAN="3"><select CLASS="'+this.cssPrefix+'cpMonthNavigation" name="cpMonth" onmouseup="CP_stop(event)" onChange="'+refresh+'('+this.index+',this.options[this.selectedIndex].value-0,'+(year-0)+');">';
for( var monthCounter=1; monthCounter<=12; monthCounter++ ) {
var selected = (monthCounter==month) ? 'SELECTED' : '';
result += '<option value="'+monthCounter+'" '+selected+'>'+this.monthNames[monthCounter-1]+'</option>';
}
result += '</select></TD>';
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="10"> </TD>';
result += '<TD CLASS="'+this.cssPrefix+'cpYearNavigation" WIDTH="56" COLSPAN="3"><select CLASS="'+this.cssPrefix+'cpYearNavigation" name="cpYear" onmouseup="CP_stop(event)" onChange="'+refresh+'('+this.index+','+month+',this.options[this.selectedIndex].value-0);">';
for( var yearCounter=year-this.yearSelectStartOffset; yearCounter<=year+this.yearSelectStartOffset; yearCounter++ ) {
var selected = (yearCounter==year) ? 'SELECTED' : '';
result += '<option value="'+yearCounter+'" '+selected+'>'+yearCounter+'</option>';
}
result += '</select></TD>';
}
else {
if (this.isShowYearNavigation) {
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="10"><A CLASS="'+this.cssPrefix+'cpMonthNavigation" HREF="'+refreshLink+'('+this.index+','+last_month+','+last_month_year+');"><</A></TD>';
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="58"><SPAN CLASS="'+this.cssPrefix+'cpMonthNavigation">'+this.monthNames[month-1]+'</SPAN></TD>';
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="10"><A CLASS="'+this.cssPrefix+'cpMonthNavigation" HREF="'+refreshLink+'('+this.index+','+next_month+','+next_month_year+');">></A></TD>';
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="10"> </TD>';
result += '<TD CLASS="'+this.cssPrefix+'cpYearNavigation" WIDTH="10"><A CLASS="'+this.cssPrefix+'cpYearNavigation" HREF="'+refreshLink+'('+this.index+','+month+','+(year-1)+');"><</A></TD>';
if (this.isShowYearNavigationInput) {
result += '<TD CLASS="'+this.cssPrefix+'cpYearNavigation" WIDTH="36"><INPUT NAME="cpYear" CLASS="'+this.cssPrefix+'cpYearNavigation" SIZE="4" MAXLENGTH="4" VALUE="'+year+'" onBlur="'+refresh+'('+this.index+','+month+',this.value-0);"></TD>';
}
else {
result += '<TD CLASS="'+this.cssPrefix+'cpYearNavigation" WIDTH="36"><SPAN CLASS="'+this.cssPrefix+'cpYearNavigation">'+year+'</SPAN></TD>';
}
result += '<TD CLASS="'+this.cssPrefix+'cpYearNavigation" WIDTH="10"><A CLASS="'+this.cssPrefix+'cpYearNavigation" HREF="'+refreshLink+'('+this.index+','+month+','+(year+1)+');">></A></TD>';
}
else {
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="22"><A CLASS="'+this.cssPrefix+'cpMonthNavigation" HREF="'+refreshLink+'('+this.index+','+last_month+','+last_month_year+');"><<</A></TD>\n';
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="100"><SPAN CLASS="'+this.cssPrefix+'cpMonthNavigation">'+this.monthNames[month-1]+' '+year+'</SPAN></TD>\n';
result += '<TD CLASS="'+this.cssPrefix+'cpMonthNavigation" WIDTH="22"><A CLASS="'+this.cssPrefix+'cpMonthNavigation" HREF="'+refreshLink+'('+this.index+','+next_month+','+next_month_year+');">>></A></TD>\n';
}
}
result += '</TR></TABLE>\n';
result += '<TABLE WIDTH=120 BORDER=0 CELLSPACING=0 CELLPADDING=1 ALIGN=CENTER>\n';
result += '<TR>\n';
for (var j=0; j<7; j++) {
result += '<TD CLASS="'+this.cssPrefix+'cpDayColumnHeader" WIDTH="14%"><SPAN CLASS="'+this.cssPrefix+'cpDayColumnHeader">'+this.dayHeaders[(this.weekStartDay+j)%7]+'</TD>\n';
}
result += '</TR>\n';
for (var row=1; row<=6; row++) {
result += '<TR>\n';
for (var col=1; col<=7; col++) {
var disabled=false;
if (this.disabledDatesExpression!="") {
var ds=""+display_year+LZ(display_month)+LZ(display_date);
eval("disabled=("+this.disabledDatesExpression+")");
}
var dateClass = "";
if ((display_month == this.currentDate.getMonth()+1) && (display_date==this.currentDate.getDate()) && (display_year==this.currentDate.getFullYear())) {
dateClass = "cpCurrentDate";
}
else if (display_month == month) {
dateClass = "cpCurrentMonthDate";
}
else {
dateClass = "cpOtherMonthDate";
}
if (disabled || this.disabledWeekDays[col-1]) {
result += ' <TD CLASS="'+this.cssPrefix+dateClass+'"><SPAN CLASS="'+this.cssPrefix+dateClass+'Disabled">'+display_date+'</SPAN></TD>\n';
}
else {
var selected_date = display_date;
var selected_month = display_month;
var selected_year = display_year;
if (this.displayType=="week-end") {
var d = new Date(selected_year,selected_month-1,selected_date,0,0,0,0);
d.setDate(d.getDate() + (7-col));
selected_year = d.getYear();
if (selected_year < 1000) { selected_year += 1900; }
selected_month = d.getMonth()+1;
selected_date = d.getDate();
}
result += ' <TD CLASS="'+this.cssPrefix+dateClass+'"><A HREF="javascript:'+windowref+this.returnFunction+'('+selected_year+','+selected_month+','+selected_date+');'+windowref+'CP_hideCalendar(\''+this.index+'\');" CLASS="'+this.cssPrefix+dateClass+'">'+display_date+'</A></TD>\n';
}
display_date++;
if (display_date > daysinmonth[display_month]) {
display_date=1;
display_month++;
}
if (display_month > 12) {
display_month=1;
display_year++;
}
}
result += '</TR>';
}
var current_weekday = now.getDay() - this.weekStartDay;
if (current_weekday < 0) {
current_weekday += 7;
}
result += '<TR>\n';
result += ' <TD COLSPAN=7 ALIGN=CENTER CLASS="'+this.cssPrefix+'cpTodayText">\n';
if (this.disabledDatesExpression!="") {
var ds=""+now.getFullYear()+LZ(now.getMonth()+1)+LZ(now.getDate());
eval("disabled=("+this.disabledDatesExpression+")");
}
if (disabled || this.disabledWeekDays[current_weekday+1]) {
result += ' <SPAN CLASS="'+this.cssPrefix+'cpTodayTextDisabled">'+this.todayText+'</SPAN>\n';
}
else {
result += ' <A CLASS="'+this.cssPrefix+'cpTodayText" HREF="javascript:'+windowref+this.returnFunction+'(\''+now.getFullYear()+'\',\''+(now.getMonth()+1)+'\',\''+now.getDate()+'\');'+windowref+'CP_hideCalendar(\''+this.index+'\');">'+this.todayText+'</A>\n';
}
result += ' <BR>\n';
result += ' </TD></TR></TABLE></CENTER></TD></TR></TABLE>\n';
}
The code I am using.....
// Author: Matt Kruse <matt@mattkruse.com>
// WWW: http://www.mattkruse.com/
