The abbreviation AJAX stands for Asynchronous JavaScript And XML. With AJAX you can get additional information after loading the web page using JavaScript. The best part of this is that the page doesn’t have to refreshed. This alows you to create interactive user interfaces within sites and web applications.
It works within any modern browser that supports JavaScript (and XML). They all do that nowadays.
Examples of AJAX
A good example of AJAX is Google suggest. When you enter a word, the list of keyword suggestions is updated.
On YouTube you often have a list of related videos. If you click on “show more”, additional suggestions will be loaded via AJAX.
AJAX is also used for Google Maps. The interface allows the user to change the location in real time.
Automaically filling out forms. You see more and more that when you fill out a form and enter your address, other fields are automatically filled in with your postcode and city.
Gmail, Basecamp, Flickr and many other sites use AJAX effectively.
How does AJAX work?
AJAX makes these fast, interactive web applications and sites using XML, HTML, CSS3 and JavaScript. AJAX uses XHTML for content, CSS3 for the design and JavaScript to display the dynamic content.
With AJAX, when the visitor clicks a submit button or even moves his computer mouse, JavaScript sends a request to the server. The results are interpreted and the current screen is updated. The visitor doesn’t realize that anything is sent to the server.
Although the “X” in AJAX stands for XML, JSON is nowadays used more often because it is lighter and a part of JavaScript. JSON is a way to store information similar to a database.