AJAX Article

Introduction

AJAX (Asynchronous JavaScript and XML) is technique which involves creating fast and dynamic web pages. It allows web pages to be updated asynchronously by exchanging small amounts of data with the server behind the scenes. This means that it is possible to update parts of a web page without reloading the whole page.

AJAX was first was introduced in 1999 by various web developers but the term 'AJAX' was only first publicly used in 2005 by Jesse James Garrett.

Features

XMLHttpRequest - This is an object within JavaScript, it is used to execute AJAX on webpages which allows new content to be loaded onto the screen without the webpage refreshing itself. This allows for increased user experience (UX) which leads to higher user rentention on webpages, rather than leaving due to constantly having to reload pages to change the content.

Interactions with many different web technologies and languages - JavaScript is used in binding most of these together which strengthens the language.

Handles respones, events, callback functions, most content, if not all can be made into a dynamic webpage, thanks to AJAX, User Interfaces are much cleaner. Pages / files with different content are loaded with the main content, so when there are requests to change the content are made, the content changes instantly.

Pros/Cons

AJAX has its pros and cons:

Pros	Cons
Improved UI (User Experience) - The enriched UI provided by AJAX is the foremost benefit. AJAX allows webpages to update serially by exchanging a small amount of data with the server. This way it is possible to update parts of a webpage, without reloading the whole page. This facilitates for faster browsing speed and thereby providing a responsive UX.	Insecurity - The web page can be difficult to debug, increases the code size of your webpage, and makes your webpage prone to severe security threats.
Enhanced User Productivity - The AJA library provides object-oriented (OO) helper functions that dramatically increase the productivity while decreasing frustration. In addition, a well-configured ASP.NET application has its own data access layer and business layer. Finally, the "robust" ASP.NET application includes a UI layer where server side operations are performed. If you already have included these features, AJAX only needs an extra layer of AJAX-specific services and some enrichment on client features. This way the deployment cost is reduced and the productivity of the user can be enhanced.	Increased load on Web Server - The load can be increased depending on the user if you are adding an auto-update type that hits the server every few seconds.
Increased Compatibility - AJAX can be compatible with ASP.NET, J2EE, PHP or any languages. It almost supports all popular browsers.	Browser Incompatibility - AJAX highly depends on JavaScript which is implemented differently for various browsers. This turns out to be a hurdle especially when AJAX has to work across many browsers. Browsers which do not support JavaScript or have the JavaScript option disabled will not be able to use its functionality. Due to the AJAX's dependancy on JavaScript, it is not suitable for designing mobile applications. For example - The back button of your web browser does not work as expected.
Easier Navigation and Asynchronous programming - AJAX applications can be built to allow easy transition between webpages to the users instead of using conventional back and forward buttons on a browser. Also asynchronous processing helps data retrieval can be done by using the XMLHttpRequest object, This means requests are handled efficiently and dynamic content loading is bought to higher heights by improving the performance considerably.

Extra Programs

AJAX is used in many different programs and is used in conjunctions in many different technologies. These are:

JavaScript, XML, HTML, CSS, JSON as well as JS Libraries.
Various APIs (Google, YouTube, etc).
Text Editors and IDEs (such as Sublime, JetBrains, etc).
Further Web Tech Frameworks such as AngularJS, Vue.js, ReactJS, Bootstrap, Foundation.
Backend technologies such as SQL and no-SQL databases.
Interacting end technologies such as C# and PHP.

Summary

In conclusion:

AJAX are an amazing bunch of technologies, and was revolutionary back in the mid 00's to help with making web pages more dynamic, however, as of the last 5 years, most of it's use has since evaporated due to the rise of more complex, dynamic, and robust JavaScript technologies such as Node.js, ReactJS, Vue.js and Angular etc. A lot of the things that these new technologies and frameworks do are much more specialised and provide a better user experience than what AJAX provided. AJAX is still used in many web applications but at a reduced role, it is still useful as there is no installation needed and it is built into JavaScript.