Running javascript within AJAX loaded object

I am creating a calendar that is loaded via AJAX, so the page does not load when click previous or next month button. Within the calendar I include another AJAX on each cell, that will show the clicked cell date. I got homepage (include calendar.php, javascript.js), when homepage is execute, there is no javascript run when I click on the calendar cell. It works when I only run calendar.php by itself.

How do I get the javascript to run inside the AJAX?

The javascript within the calendar.php, this code is stored inside javascript.js


function loadXMLDoc(var1)
{
if (window.XMLHttpRequest)
  {// code for IE7+, Firefox, Chrome, Opera, Safari
  xmlhttp=new XMLHttpRequest();
  }
else
  {// code for IE6, IE5
  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");
  }
xmlhttp.onreadystatechange=function()
  {
  if (xmlhttp.readyState==4 && xmlhttp.status==200)
    {    document.getElementById("myDiv").innerHTML=xmlhttp.responseText;
    }
  }

var passingID1 = var1; 
var url = "variables.php";
var modurl = "variables.php?passid=" + passingID1; 
xmlhttp.open("GET", modurl ,true);
xmlhttp.send();
}

My homepage


<body onLoad='navigate("","")'>

	<div id="calback">
		<div id="calendar">
		  <p>&nbsp;</p>
		  <p>&nbsp;</p>
		  <p>&nbsp;</p>
		  <p>&nbsp;</p>
		  <p>&nbsp;</p>
		  <p>&nbsp;</p>
		</div>
	</div>

<p>Selected Date
<div id="myDiv"><h2>You have selected !</h2></div>