Asynchronous JavaScript and XML – AJAX

Ajax is a technology used in web development to create dynamic and interactive user interfaces. The acronym stands for Asynchronous JavaScript and XML, and this tool allows web applications to update content on a web page without requiring a full page reload.

Before Ajax, web pages would have to refresh entirely each time a user interacted with the page.

This led to slow and clunky user experiences and made it difficult to create web applications that felt as responsive and interactive as desktop software applications. 

AJAX Elements

Ajax was introduced in the early 2000s to address these issues. It uses a combination of JavaScript, the Document Object Model (DOM), and XMLHttpRequest (XHR) to asynchronously retrieve server data and update web page parts without requiring a full page reload.

So, let’s quickly cover their functions:

• JavaScript is a programming language for developing interactive web pages. It can manipulate the DOM, which represents a web page’s structure and content. All modern browsers support JavaScript.
• DOM stands for Document Object Model and is a way for JavaScript to access and manipulate the elements of a web page.
• XMLHttpRequest is an API (Application Programming Interface) that allows JavaScript to make HTTP requests to a server and receive data in various formats, including XML, JSON, and HTML.

The AJAX Process

When a user interacts with a web page that uses Ajax, JavaScript sends an HTTP request to the server using XMLHttpRequest. This request can include data that the server needs to process the request, such as user input or the current state of the page.

Once the server receives the request, it processes it and sends back a response, usually in a format like XML or JSON. This response can include new data that the web page needs to display, such as updated content or new options for a dropdown menu.

When the web page receives the response, JavaScript can use the DOM to update the relevant parts of the page with the new data. Depending on the scenario, this update process can happen with or without the user having to initiate it, thus creating a seamless and responsive user experience.

Interactive User Experiences

One of the critical benefits of Ajax is that it allows web applications to feel more like desktop applications, with faster and more responsive interfaces. It also allows for more dynamic and interactive interfaces, such as auto-complete search bars and real-time content updates.

For example, a stock price page may update stock price information every so many seconds for a live display.

An example where the user initiates an AJAX-driven request could be clicking a button to request shipping cost information based on the address that the user provided. 

Lighter Server Workloads

Another benefit of Ajax is that it can reduce the amount of data that the server and client device transfer to each other. Ajax requests to the server are only for updates to specific parts of the web page, so it can reduce the amount of data compared to transmitting the full page each time over the network.

AJAX’s focus on just a particular piece of web page data can lead to faster load times and a better user experience, especially for users on slow or unreliable connections.

Conclusion

Ajax has become an essential technology for modern web development. It allows developers to create more dynamic and interactive web applications that feel more like desktop software applications without sacrificing performance or speed.

Demo of AJAX calls in code – 3 mins