IT DefinitionJavaScript

What Is AJAX?

AJAX is an acronym for “Asynchronous JavaScript and XML”. This web technology enables individual components of a website to be loaded dynamically so that the entire website does not need to be reloaded. Content can be manipulated in a targeted manner, which improves the user experience and the usability of the website.

What is AJAX?

Modern websites offer a high degree of interactivity and must be able to react dynamically to user input. When creating an e-mail account, for example, before the data is transmitted, it could be checked whether the desired e-mail address is available or whether the password meets the minimum level of security. Such and similar scenarios can only be implemented if individual components of the website can be manipulated regardless of the moment at which the website is loaded. AJAX is a procedure with which this asynchronous data transfer between server and client can be implemented.

The greatest advantage of AJAX is that websites no longer have to be completely reloaded in order to react to user input. Static content remains unchanged, while dynamic information can be added to the DOM (Document Object Model) as required. In the above example with the creation of a new e-mail account, a request must be sent to the responsible web server so that it can check whether the desired username is available.

Without AJAX, the form had to be sent and the entire website reloaded. The innovative web technology enables a request to be sent to the server at any time through the use of JavaScript. The result of this query decides whether a message should be added to the Document Object Model or not. The dynamic generation of website elements such as drop-down lists is also possible with AJAX. For example, only selection options that match the previously selected options can be displayed.
Instead of having to lead users to a new website for each new step, only certain parts of the page with the relevant content are changed. This not only saves time but also bandwidth and offers a better user experience.

How does AJAX work?

The script language JavaScript is used to dynamically change parts of a website. JavaScript is executed on the visitor’s computer within the browser environment and therefore works even after the page has already been loaded. This makes it possible to send a request to the webserver at any time in order to subsequently request certain data and then display this dynamically on the website.

From a technical point of view, JavaScript is combined with XML (Extensible Markup Language) to enable asynchronous updates through the use of a so-called “XMLHttpRequest object”. When a user calls up a web presence intended for the use of AJAX and a prescribed event is triggered, JavaScript automatically creates an XMLHttpRequest object that is responsible for the asynchronous data transfer between the client and the server.

The XMLHttpRequest object sends a request to the responsible web server for an update of certain data on the website. The server processes the request, creates a response, and then sends it back to the client. JavaScript is then used on the client-side to process the response and dynamically change content and display it on the screen. Many web developers use special frameworks such as jQuery or Axios, which are based on JavaScript and were specially developed for the convenient and browser-independent manipulation of DOM elements in the World Wide Web. Such frameworks make the development of AJAX applications easier and, compared to JavaScript, offer a short and precise expression.


Properties and special features of AJAX

As we have already mentioned in the above paragraph, the functionality of traditional websites and web applications can be described with the principle of “stop and go”: the visitor triggers an action on a website and waits for the responsible server to process this action and the website then updated.

With AJAX applications, server requests are started in the background without having to change an HTML document. This means that there is no longer any need to wait for a response from the responsible web server, or the server only has to send back a small data packet. The main advantage of Ajax-based web applications is that they react much faster to user actions and thus come closer to the smooth behavior of native apps and desktop applications. This has an extremely positive effect on the user experience and usability.

AJAX technology intentionally breaks with the traditional workings and rules of the World Wide Web. It is precisely from this that it draws its advantages, but also some disadvantages. The main disadvantage is reflected in the fact that there are no longer any fully addressable HTML documents in Ajax-based applications, so that the return function no longer works as usual in many cases. This is due to the fact that the changes to the content via JavaScript are not registered in the browser history, since the HTML document has not been exchanged and the URL has not changed. Navigation, as you are used to from static web presences, is not possible on Ajax-based web pages.

How can I use AJAX when developing?

As we already mentioned in the above paragraph, the “J” in AJAX stands for the scripting language JavaScript, which is used in the context of the World Wide Web for programming website processes. JavaScript is primarily used to dynamically create, add, and manage web content. After static web features such as headers, fonts and paragraphs have been implemented with the two markup languages HTML and CSS, JavaScript is then used to give the web presence the necessary functionality.

The “X” in AJAX stands for “Extensible Markup Language”. This is the XML markup language. While page content is defined and designed with HTML and CSS, XML is used for asynchronous data transfer.

Ajax-based web applications are usually developed using modern JavaScript frameworks. The most popular JS frameworks used on the client-side include React, Angular, and jQuery. The server code of an AJAX web application is not necessarily linked to JavaScript and can be implemented in different programming languages such as PHP, .NET Core, or Java.

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