/* common method to get XMLHttp request object */
function getXMLHttpRequest()
{
var req;
if (window.XMLHttpRequest) { // For Firefox, Mozilla, Safari, …
req = new XMLHttpRequest();
}
else if (window.ActiveXObject) { // For IE
try {
req = new ActiveXObject("Msxml2.XMLHTTP");
}
catch (e) {
try {
req = new ActiveXObject("Microsoft.XMLHTTP");
}
catch (e) {}
}
}
return req;
}

/* method for dynamically getting current time in milliseconds and append that value to no-cache parameter
* IE browser does not send ajax request if the url is same, simply get result from cache
* to avoid this and make a new request, we append no-cache param to each ajax request.
*/
function getNoCacheValue(url)
{
var d = new Date();
var appendstring = (url.indexOf("?") != -1) ? "&" : "?";
var nocachevalue = appendstring + "no-cache=" + d.getTime();
return nocachevalue
}

/* method to send a ajax request, and write the response text to given divid. */
function sendAjaxRequest(url, divid)
{
url = url + getNoCacheValue(url);
var req = getXMLHttpRequest();
req.onreadystatechange = function(){ processResponse(req, divid) };
req.open('GET', url, true);
req.send(null);
}

function processResponse(req, divid)
{
if (req.readyState == 4) {
if (req.status == 200) {
document.getElementById(divid).innerHTML=req.responseText;
invokeScript(document.getElementById(divid));
}
}
}

/* method for executing script separately.
* (scenario :  send a Ajax request, response is HTML with some scripts - scripts in response HTML should not load )
* to overcome this issue, we used this method to load the scripts separately.
*/
function invokeScript(divid)
{
var scriptObj = divid.getElementsByTagName("SCRIPT");
var len = scriptObj.length;
for(var i=0; i<len; i++)
{
var scriptText = scriptObj[i].text;
var scriptFile = scriptObj[i].src
var scriptTag = document.createElement("SCRIPT");
if ((scriptFile != null) && (scriptFile != "")){
scriptTag.src = scriptFile;
}
scriptTag.text = scriptText;
if (!document.getElementsByTagName("HEAD")[0]) {
document.createElement("HEAD").appendChild(scriptTag)
}
else {
document.getElementsByTagName("HEAD")[0].appendChild(scriptTag);
}
}
}