JavaScript - Calendar Control In Javascript

Hello friends...
i am working on the healthcare project.In which there are user interactive pages such as registration page,profile page.
In registration page to register the portal the birth date of user is required .
so i have added the calendar control using javascript.
I want that whenever user clicks on the calendar the birth date is displayed in the textfield.
but it cannot displayed the birth date...
So please tell me the sloution...

following is the code for calendar control

<p>
<meta content="text/html;" http-equiv="Content-Type" />
<style type="text/css">
#calender { width: 200px; font-family: ms sans serif, sans serif; font-size: 7pt; }
#calenderTable { border-style: outset; border-width: 2px; border-color: black; background-color: #EEE; display: none; position: absolute; z-index: 1; top: 0px; left: 0px; }
#calenderTableHead TR { background-color: #5FB404; }
#calenderTableDays TR { background-color: #B40404; color: #E6E6E6; }
.normalDay { border: 1px dotted black; cursor: pointer; }
.hlDay { border: 1px black; background-color: #585858; color: #E6E6E6; cursor: pointer; }
.toDay { border: 1px solid #E70; background-color: #FD8; color: #E70; font-weight: bold; cursor: pointer; }
.choosenDay { border: 1px #000000; background-color: #585858; color: #E6E6E6; font-weight: bold; cursor: pointer; }
</style>
<link rel="stylesheet" type="text/css" href="calendar.css" />
<script language="javaScript" type="text/javascript" src="calendar.js">
// Array of max days in month in a year and in a leap year
monthMaxDays = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
monthMaxDaysLeap= [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
hideSelectTags = [];
function getRealYear(dateObj)
{
return (dateObj.getYear() % 100) + (((dateObj.getYear() % 100) < 39) ? 2000 : 1900);
}
function getDaysPerMonth(month, year)
{
/* Check for leap year. These are some conditions to check year is leap year or not... 1.Years evenly divisible by four are normally leap years, except for... 2.Years also evenly divisible by 100 are not leap years, except for... 3.Years also evenly divisible by 400 are leap years. */
if ((year % 4) == 0)
{
if ((year % 100) == 0 && (year % 400) != 0)
return monthMaxDays[month];
return monthMaxDaysLeap[month];
}
else return monthMaxDays[month];
}

function createCalender(year, month, day)
{
// current Date
var curDate = new Date();
var curDay = curDate.getDate();
var curMonth = curDate.getMonth();
var curYear = getRealYear(curDate)
// if a date already exists, we calculate some values here
if (!year)
{
var year = curYear; var month = curMonth;
}
var yearFound = 0;
for (var i=0; i<document.getElementById('selectYear').options.length; i++)
{
if (document.getElementById('selectYear').options[i].value == year)
{
document.getElementById('selectYear').selectedIndex = i;
yearFound = true;
break;
}
}
if (!yearFound)
{
document.getElementById('selectYear').selectedIndex = 0;
year = document.getElementById('selectYear').options[0].value;
}
document.getElementById('selectMonth').selectedIndex = month;

// first day of the month.
var fristDayOfMonthObj = new Date(year, month, 1);
var firstDayOfMonth = fristDayOfMonthObj.getDay();
continu = true;
firstRow = true; var x = 0; var d = 0; var trs = [] var ti = 0;
while (d <= getDaysPerMonth(month, year))
{
if (firstRow)
{
trs[ti] = document.createElement("TR");
if (firstDayOfMonth > 0)
{
while (x < firstDayOfMonth)
{
trs[ti].appendChild(document.createElement("TD")); x++;
}
}
firstRow = false; var d = 1;
}

if (x % 7 == 0)
{
ti++; trs[ti] = document.createElement("TR");
}
if (day && d == day)
{
var setID = 'calenderChoosenDay';
var styleClass = 'choosenDay';
var setTitle = 'this day is currently selected';
}
else if (d == curDay && month == curMonth && year == curYear)
{
var setID = 'calenderToDay';
var styleClass = 'toDay';
var setTitle = 'this day today';
}
else
{
var setID = false; var styleClass = 'normalDay'; var setTitle = false;
}
var td = document.createElement("TD");
td.className = styleClass; if (setID)
{
td.id = setID;
}
if (setTitle)
{
td.title = setTitle;
}
td.onmouseover = new Function('highLiteDay(this)');
td.onmouseout = new Function('deHighLiteDay(this)');
if (targetEl)
td.onclick = new Function('pickDate('+year+', '+month+', '+d+')');
else td.style.cursor = 'default'; td.appendChild(document.createTextNode(d));
trs[ti].appendChild(td); x++; d++;
}
return trs;
}

function showCalender(elPos, tgtEl)
{
targetEl = false;
if (document.getElementById(tgtEl))
{
targetEl = document.getElementById(tgtEl);
}
else
{
if (document.forms[0].elements[tgtEl])
{
targetEl = document.forms[0].elements[tgtEl];
}
}
var calTable = document.getElementById('calenderTable');
var positions = [0,0];
var positions = getParentOffset(elPos, positions);
calTable.style.left = positions[0]+'px';
calTable.style.top = positions[1]+'px';
calTable.style.display='block';
var matchDate = new RegExp('^([0-9]{2})-([0-9]{2})-([0-9]{4})$');
var m = matchDate.exec(targetEl.value);
if (m == null)
{
trs = createCalender(false, false, false);
showCalenderBody(trs);
}
else
{
if (m[1].substr(0, 1) == 0) m[1] = m[1].substr(1, 1);
if (m[2].substr(0, 1) == 0) m[2] = m[2].substr(1, 1); m[2] = m[2] - 1;
trs = createCalender(m[3], m[2], m[1]);
showCalenderBody(trs);
}
hideSelect(document.body, 1);
}

function showCalenderBody(trs)
{
var calTBody = document.getElementById('calender');
while (calTBody.childNodes[0])
{
calTBody.removeChild(calTBody.childNodes[0]);
}
for (var i in trs)
{
calTBody.appendChild(trs[i]);
}
}
function setYears(sy, ey)
{
// current Date
var curDate = new Date();
var curYear = getRealYear(curDate);
if (sy) startYear = curYear;
if (ey) endYear = curYear;
document.getElementById('selectYear').options.length = 0;
var j = 0;
for (y=ey; y>=sy; y--)
{
document.getElementById('selectYear')[j++] = new Option(y, y);
}
}
function hideSelect(el, superTotal)
{
if (superTotal >= 100) { return; }
var totalChilds = el.childNodes.length;
for (var c=0; c<totalChilds; c++)
{
var thisTag = el.childNodes[c];
if (thisTag.tagName == 'SELECT')
{
if (thisTag.id != 'selectMonth' && thisTag.id != 'selectYear')
{
var calenderEl = document.getElementById('calenderTable');
var positions = [0,0];
var positions = getParentOffset(thisTag, positions);
// nieuw
var thisLeft = positions[0];
var thisRight = positions[0] + thisTag.offsetWidth;
var thisTop = positions[1];
var thisBottom = positions[1] + thisTag.offsetHeight;
var calLeft = calenderEl.offsetLeft;
var calRight = calenderEl.offsetLeft + calenderEl.offsetWidth;
var calTop = calenderEl.offsetTop;
var calBottom = calenderEl.offsetTop + calenderEl.offsetHeight;
if ( ( /* check if it overlaps horizontally */ (thisLeft >= calLeft && thisLeft <= calRight) || (thisRight <= calRight && thisRight >= calLeft) || (thisLeft <= calLeft && thisRight >= calRight) ) && ( /* check if it overlaps vertically */ (thisTop >= calTop && thisTop <= calBottom) || (thisBottom <= calBottom && thisBottom >= calTop) || (thisTop <= calTop && thisBottom >= calBottom) ) )
{
hideSelectTags[hideSelectTags.length] = thisTag; Tag.style.display = 'none';
}
}
}
else if(thisTag.childNodes.length > 0)
{
hideSelect(thisTag, (superTotal+1));
}
}
}
function closeCalender()
{
for (var i=0; i<hideSelectTags.length; i++)
{
hideSelectTags[i].style.display = 'block';
}
hideSelectTags.length = 0;
document.getElementById('calenderTable').style.display='none';
}

function highLiteDay(el) { el.className = 'hlDay'; }
function deHighLiteDay(el)
{
if (el.id == 'calenderToDay') el.className = 'toDay';
else if (el.id == 'calenderChoosenDay') el.className = 'choosenDay';
else el.className = 'normalDay';
}

function pickDate(year, month, day)
{
month++;
day = day < 10 ? '0'+day : day;
month = month < 10 ? '0'+month : month;
if (!targetEl)
{
alert('target for date is not set yet');
}
else
{
targetEl.value= day+'-'+month+'-'+year; closeCalender();
}
}
function getParentOffset(el, positions)
{
positions[0] += el.offsetLeft; positions[1] += el.offsetTop; if (el.offsetParent) positions = getParentOffset(el.offsetParent, positions); return positions;
}
</script>
<link rel="stylesheet" type="text/css" href="calendar.css" /></p>
<form>
<input name="datum1" type="text" /><a onClick="setYears(1900, 2020); showCalender(this, 'datum1');" href="#"> <img alt="" width="17" height="13" src="/image/image_gallery?uuid=ad0e28d1-ae91-4535-a558-32d62a7df92e&amp;groupId=10136&amp;t=1294233035464" /></a>
</form>
<!-- Calender Script -->
<table id="calenderTable">
<tbody id="calenderTableHead">
<tr>
<td colspan="4" align="center"><select id="selectMonth" onChange="showCalenderBody(createCalender(document.getElementById('selectYear').value, this.selectedIndex, false));">
<option value="0" selected="selected">Jan</option>
<option value="1">Feb</option>
<option value="2">Mar</option>
<option value="3">Apr</option>
<option value="4">May</option>
<option value="5">Jun</option>
<option value="6">Jul</option>
<option value="7">Aug</option>
<option value="8">Sep</option>
<option value="9">Oct</option>
<option value="10">Nov</option>
<option value="11">Dec</option>
</select></td>
<td colspan="2" align="center"><select id="selectYear" onChange="showCalenderBody(createCalender(this.value, document.getElementById('selectMonth').selectedIndex, false));"></select></td>
<td align="center"><a onClick="closeCalender();" href="#"><font color="#003333" size="+1">X</font></a></td>
</tr>
</tbody>
<tbody id="calenderTableDays">
<tr>
<td>Sun</td>
<td>Mon</td>
<td>Tue</td>
<td>Wed</td>
<td>Thu</td>
<td>Fri</td>
<td>Sat</td>
</tr>
</tbody>
<tbody id="calender">
</tbody>
</table>
<!-- End Calender Script -->

Thanking you...