Dynamiczny kalendarz w JavaScript z przykładem

<!DOCTYPE html>
<html>
<head>
<style type="text/css">
.calendarMonth{
border-collapse:collapse;
background-color:#eef;
}
.calendarMonth th{
}
.calendarMonth .calendarTitle{
background-color:#ddf;
}
.calendarMonth .calendarPrevious{
background-color:#ddf;
}
.calendarMonth .calendarNext{
background-color:#ddf;
}
.calendarEmpty{
}
.calendarDay{
background:#fff;
border:1px solid black;
text-align:center;
width:2em;
}
</style>

<script type="text/javascript">
var  daysInMonth=[31,28,31,30,31,30,31,31,30,31,30,31];
var  monthNames=['January','February','March','April','May','June','July','August','September','October','November','December'];

// Returns the number of days in the month in a given year (January=0)
function getDaysInMonth(month,year){
if ((month==1)&&(year%4==0)&&((year%100!=0)||(year%400==0))){
return 29;
}else{
return daysInMonth[month];
}
}

// Performs an action when a date is clicked
function dateClicked(day,month,year){
document.forms.calendar.date.value = day+'/'+month+'/'+year;  

}

// Sets the displayed month
function setDisplayedMonth(month){
if (month<0){
alert('You have reached the beginning of this calendar');
}else if (month>=months){
alert('You have reached the end of this calendar');
}else{
for (var i=0;i<months;i++){
document.getElementById('calendarMonth'+i).style.display='none';
}
document.getElementById('calendarMonth'+month).style.display='block';
}
}
</script>
</head> 

<body>
<form id="calendar">
<table>
<tr>
<td><label for="date">Date:</label></td>
<td><input type="text" id="date" name="date" value="28/05/2015"></td>
</tr>
<tr><td></td><td>
<script type="text/javascript">
var month=0;
var year=2015;
var months=12;
for (var i=0;i<months;i++){
document.writeln('<table class="calendarMonth" '+'id="calendarMonth'+i+'" cellspacing="0">');
 document.writeln('<tr>'
          +'<th class="calendarPrevious" onClick="setDisplayedMonth('+(i-1)+')"><</th>'+'<th class="calendarTitle" colspan="5">'            +monthNames[month]+' '+year+'</th>'+'<th class="calendarNext" onClick="setDisplayedMonth('+(i+1)+')">></th>'+'</tr>');

document.writeln('<tr><th>Sun</th><th>Mon</th><th>Tue</th>'+'<th>Wed</th><th>Thu</th><th>Fri</th><th>Sat</th></tr>');
var firstDayDate=new Date(year,month,1);
var firstDay=firstDayDate.getDay();
for (j=0;j<42;j++){
if (j%7==0) document.write('<tr>')
if ((j=firstDay+getDaysInMonth(month,year))){
document.write('<td class="calendarEmpty"></td>');
}else{
document.write('<td class="calendarDay" '+'onClick="dateClicked('+(j-firstDay+1)+','+(month+1)+','+year+')">'+(j-firstDay+1)+'');
}
if (j%7==6) document.write('</tr>');
}
document.writeln('</table>');
month++;
if (month>=12){
month=0;
year++;
}
}
setDisplayedMonth(5);
</script>
</td></tr>
</table>
</form>
</body>
</html>
Yog