A simple version of the code that we will use for cross browser:
// creates XMLHttpRequest Instance
function createXmlHttpRequestObject(){
// will store XMLHttpRequest object
// at here
var xmlHttp;
// works all exceprt IE6 and older
try
{
// try to create XMLHttpRequest object
xmlHttp = new XMLHttpRequest();
}
catch(e)
{
// assume IE 6 or older
try
{
xmlHttp = new ActiveObject("Microsoft.XMLHttp");
}
catch(e){ }
}
// return object or display error
if (!xmlHttp)
alert("Error creating the XMLHttpRequest Object");
else
return xmlHttp;
}