There are two ways to use XMLHttp request, one for IE(Internet Explorer) by using ActiveXobject and other for on IE borwsers (Firefox, safari and opera) by use XMLHttpRequest().
following example shows how it work:
//Create a boolean variable to check for a valid Internet Explorer instance.
var xmlhttp = false;
//Check if we are using IE.
try {
//If the Javascript version is greater than 5.
xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
alert ("You are using Microsoft Internet Explorer.");
}
catch (e)
{
//If not, then use the older active x object.
try {
//If we are using Internet Explorer.
xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
alert ("You are using Microsoft Internet Explorer");
}
catch (E)
{
//Else we must be using a non-IE browser.
xmlhttp = false;
}
}
//If we are using a non-IE browser, create a javascript instance of the object.
if (!xmlhttp && typeof XMLHttpRequest != 'undefined')
{
xmlhttp = new XMLHttpRequest();
alert ("You are not using Microsoft Internet Explorer");
}
Library for creating XMLHttp request
