Introduction to AJAX

AJAX is a technique that allows parts of a web page to be updated without reloading the entire page.

Prerequisites

Before continuing, you should have a basic understanding of the following:

• HTML / XHTML
• CSS
• JavaScript / DOM

If you wish to learn these topics first, please visit our homepage for tutorials.

What is AJAX?

AJAX stands for Asynchronous JavaScript and XML.

AJAX is a technique for creating fast and dynamic web pages.

By exchanging small amounts of data with the server in the background, AJAX allows web pages to update asynchronously. This means that parts of a web page can be updated without reloading the entire page.

Traditional web pages (without AJAX) would need to reload the entire page to update content.

Many applications use AJAX, such as Sina Weibo, Google Maps, and Kaixin001.

How AJAX Works

AJAX is Based on Existing Internet Standards

AJAX is based on existing Internet standards and combines them:

• XMLHttpRequest object (for asynchronous data exchange with the server)
• JavaScript/DOM (for information display and interaction)
• CSS (for styling data)
• XML (as a format for data transformation)

Google Suggest

In 2005, Google made AJAX popular with its Google Suggest.

Google Suggest uses AJAX to create a highly dynamic web interface: as you type keywords into Google's search box, JavaScript sends these characters to the server, which returns a list of search suggestions.

Start Using AJAX Today

AJAX is based on existing standards. These standards have been used by most developers for many years.

Please read the next chapter to see how AJAX works!