I don't understand why it's being called Ajax either; Ajax is an *approach* (like "environmentally friendly"), not a *thing*.

Anyway, you don't need to save the request object in a global variable. Assign a closure to onreadystatechange:

. // request is an XmlHTTPRequest object

request.onreadystatechange = function() {
if (request.readyState == 4 && request.status ==200) { // do something to request
}
};