⟩ How do we handle concurrent AJAX requests?
With JavaScript you can have more than one AJAX request processing at a single time. In order to insure the proper post processing of code it is recommended that you use JavaScript Closures. The example below shows an XMLHttpRequest object abstracted by a JavaScript object called AJAXInteraction. As arguments you pass in the URL to call and the function to call when the processing is done.
function AJAXInteraction(url, callback) {
var req = init();
req.onreadystatechange = processRequest;
function init() {
if (window.XMLHttpRequest) {
return new XMLHttpRequest();
} else if (window.ActiveXObject) {
return new ActiveXObject("Microsoft.XMLHTTP");
}
}
function processRequest () {
if (req.readyState == 4) {
if (req.status == 200) {
if (callback) callback(req.responseXML);
}
}
}
this.doGet = function() {
req.open("GET", url, true);
req.send(null);
}
this.doPost = function(body) {
req.open("POST", url, true);
req.setRequestHeader("Content-Type", "
application/x-www-form-urlencoded");
req.send(body);
}
}
