What is AJAX with XML?

Estimated study time: 12 minutes.

AJAX (Asynchronous JavaScript and XML) is a technique that lets a web page talk to a server in the background and update itself without a full page reload. Even though modern apps mostly send JSON, AJAX was originally built around XML — hence the name.

Why AJAX Was a Big Deal

Before AJAX, any interaction with the server (submitting a form, loading new data) meant reloading the entire page. AJAX changed that by letting JavaScript send requests and receive responses behind the scenes, updating only the parts of the page that needed to change.

The Core Idea

1. JavaScript sends a request to the server (using XMLHttpRequest or fetch)
2. The server processes the request and sends back data (XML or JSON)
3. JavaScript reads the response and updates the page — no reload needed

Where XML Fits In

In classic AJAX, the server would respond with an XML document. The browser could parse that XML directly into a DOM-like structure using the responseXML property, then pull out the values it needed to display.