Javascript: A simple calendar with today's date highlighted.

<style type="text/css">
.tdoutput {font: normal 10px "arial", "sans-serif"; color: black;}
.tdheader {font: normal 12px "arial", "sans-serif"; color: black;}
</style> 

<script language="javascript" type="text/javascript">
<!-- Begin
var day_of_week = new Array('Sun','Mon','Tue','Wed','Thu','Fri','Sat');
var month_of_year = new Array('January','February','March','April','May','June','July','August','September','October','November','December');
var Calendar = new Date();
var year = Calendar.getFullYear();      // Returns year
var month = Calendar.getMonth();        // Returns month (0-11)
var today = Calendar.getDate();         // Returns day (1-31)
var weekday = Calendar.getDay();        // Returns day (1-31)
var DAYS_OF_WEEK = 7;                   // "constant" for number of days in a week
var DAYS_OF_MONTH = 31;                 // "constant" for number of days in a month
var cal;                               // Used for printing

Calendar.setDate(1);                   // Start the calendar day at '1'
Calendar.setMonth(month);              // Start the calendar month at now

var TR_start = '<tr>';
var TR_end = '</tr>';
var highlight_start = '<td width="30"><table style="border: 1px solid" bordercolor=999999 cellspacing=0 bgcolor=yellow><tr><td width=20><B><center>';
var highlight_end   = '</center></td></tr></table></B>';
var TD_start = '<td width="30" class=tdoutput><center>';
var TD_end = '</center></td>';

cal =  '<table style="border: 1px solid" cellspacing=0 cellpadding=0 bordercolor=999999><TR><TD class=tdoutput>';
cal += '<table border=0 cellspacing=0 cellpadding=2>' + TR_start;
cal += '<td colspan="' + DAYS_OF_WEEK + '" bgcolor="#EFEFEF" class="tdheader"><CENTER><B>';
cal += month_of_year[month]  + '   ' + year + '</B>' + TD_end + TR_end;
cal += TR_start;

// do not modify the code below
// loops for each day of week
for(index=0; index < DAYS_OF_WEEK; index++)
{

// highlight today day fof week
if(weekday == index)
cal += TD_start + '<B>' + day_of_week[index] + '</B>' + TD_end;

// prints day
else
cal += TD_start + day_of_week[index] + TD_end;
}

cal += TD_end + TR_end;
cal += TR_start;

// fill in the blank gaps until today's day
for(index=0; index < Calendar.getDay(); index++)
cal += TD_start + '  ' + TD_end;

// loops for each day in the calendar
for(index=0; index < DAYS_OF_MONTH; index++)
{
if( Calendar.getDate() > index )
{
  // returns the next day to print
  week_day =Calendar.getDay();

  // start the next new row for the first day of the week
  if(week_day == 0)
  cal += TR_start;

  if(week_day != DAYS_OF_WEEK)
  {

  // set the variable which is inside the loop for incrementing
  var day  = Calendar.getDate();

  // highlight today's date
  if( today==Calendar.getDate() )
  cal += highlight_start + day + highlight_end + TD_end;

  // prints day
  else
  cal += TD_start + day + TD_end;
  }

  // end row for last day of the week
  if(week_day == DAYS_OF_WEEK)
  cal += TR_end;
  }

  // increments until the end of the month
  Calendar.setDate(Calendar.getDate()+1);

}// end for loop

cal += '</td></tr></table></table>';

//  print calendar
document.write(cal);

//  End -->
</script>