What is Ajax?

This tutorial was first aim to provide just the fundamental of Ajax Technologies. I always believe, programmers should understand how things work in order to be a good engineer. To understand better how things work, we must first dive deep into the fundamental. With the fundamental of Ajax, you'll get to know the underlying technologies, having said that, most programmers write high-level web based applications, with popular Javascript framework and libraries, we rarely need to write the low-level code for Ajax anymore. Hence, I will be adding more content for practical use.

Ajax (an acronym for Asynchronous JavaScript and XML) is a group of technologies that help you create asynchronous web applications.

The keyword is "Asynchronous".

It simply means, you can send data to, and retrieve data from, a server in the background. While waiting for response of the server, user can still use the web page as usual without a complete page refresh or interruption.

The "thing" that helps us interacting with server without refreshing a web page is called XMLHttpRequest (XHR). XHR is the agent that does all the Ajax magic tricks. XMLHttpRequest is a JavaScript object that was designed by Microsoft and adopted by Mozilla, Apple, and Google. It's now a living standard.

Despite the technology was first created by Microsoft for its Outlook Web Access (basically a web mail version of Microsoft Exchange), but Google was the company that surpised the world of Ajax techniques in Google Suggest, Google Maps and Gmail.

The rest of technologies are not something you unfamiliar with, they are HTML, CSS, XML, Javascript, Document Object Model.

Despite the name, the use of XML is not neccessary required, ironically, JSON is a more favorable variant.