What Is AJAX?

AJAX is a technique that combines other technologies like HTML, XMLHttpRequest, JavaScript, Document Object Model (DOM), and many more. It is not a programming language but rather a feature that helps users modify and display data without going through the hassle of reloading the entire page. 

When it comes to web development, HTML, CSS, and JavaScript are the first concepts that will come up in any search results and books. This is because these programming languages serve as the foundation of web pages and are termed front-end programming languages. Are these, however, the only concepts you need to be aware of?

Learning web development is similar to studying the universe. The information base is vast, and innovative ideas for enhancing website performance emerge on a regular basis. AJAX is one of those critical concepts that must be included in any web development project.

What Does AJAX Stand for?   

The acronym AJAX (Asynchronous JavaScript and XML) stands for “Asynchronous JavaScript and XML.” It describes how data is transmitted and received asynchronously without requiring the page to be reloaded entirely. As a result, the use of AJAX improves the website’s efficiency and performance.   

What Is AJAX In JavaScript?

A website that loads whenever the user enters data dampens the user performance and takes too much time to complete a particular task. Developers use the AJAX notion in their projects to avoid such unease. Now there arises another question, where is AJAX implemented?

AJAX is implemented in JavaScript. To interact with the server, AJAX employs the XMLHttpRequest (XHR) object.

The role of AJAX is to send or receive data from the server without loading the entire web page. With the help of the XMLHttpRequest object in JavaScript, an HTTP request is sent to the server whenever the user updates information. The server, in return, either saves or displays the information on the website content in real-time.

The process of AJAX is as follows:

  • An event occurs on the web page. (e.g., any information is updated or a button is clicked).
  • The JavaScript creates an XMLHttpRequest object.
  • The XMLHttpRequest object that was created delivers a request to the server.
  • The server responds to the request by processing it.
  • JavaScript analyzes the response, and the appropriate action is taken.

The web page decides whether the data is saved or displayed. AJAX is usually used in web pages that require small bits of information to be stored and displayed.   

How to Implement AJAX In JavaScript?

To implement AJAX is to instantiate an XMLHttpRequest object in JavaScript. The XMLHttpRequest object plays a key role in sending and receiving data from the server, supported by most internet browsers like Chrome, Mozilla, etc.

  • Create XMLHttpRequest Object: Before creating a callback function, XMLHttpRequest object is created.

Syntax:

variable = new XMLHttpRequest();

  • Create a Callback Function: The callback function contains the code to be executed after the response is processed.

Syntax:

xhttp.onload = function() {

// instructions are executed after the response is ready

}

  • To Send A Request: The open() and send() methods are used to send requests to the server.

Syntax:

xhttp.open(“GET”, “AJAX_info.txt”);

xhttp.send();

XMLHttpRequest Object Properties  

Property

Description

onreadystatechange

When the readyState property changes, this method is invoked.

readyState

The readyState represents the XMLHttpRequest’s current status. The following are its states and their meaning:

0: the function open() is not initialised

1: the open() function is called but send() is not called

2: request received i.e, both the open() and send() functions are received

3: processing request

4: request finished, and response is ready

responseText

The response data returns as a string.

responseXML

The response data is returned as XML data.

status

Returns the status number of a request

200: “OK”

403: “Forbidden”

404: “Not Found”

statusText

Returns the status-text (e.g. “OK” or “Not Found”)

Benefits of AJAX 

The versatility of AJAX is as follows:

  • Loads Web Pages Faster: AJAX sends callbacks to the server on specific events only, thus avoiding the need to load the complete page. Web pages load swiftly and efficiently as a result.
  • User-Friendly: Since the likelihood of an entire page loading is slim to none, web pages are more responsive and efficient, making them more user-friendly.
  • A Useful Feature For Websites: AJAX is a convenient tool for displaying real-time data. For example, live sports matches’ scores are presented on sports websites. The scores are periodically updated until the game is over. Online polls are another example. Every time a user votes on an online platform, such as Twitter, the percentage of voters and their alternatives are updated.
  • Cross-platform: AJAX is supported by almost every browser due to its versatility.
  • Bandwidth Usage Can Be Reduced: Instead of delivering the entire page’s content, this technique assists in retrieving partial contents to make the best use of the server’s bandwidth.
  • Form Validation: Unlike traditional form validation, which shows the validations after the form is submitted, AJAX delivers instant form validation. 

Conclusion

The concepts and features of AJAX are discussed in this article. AJAX expertise is required for a smoother website experience. 

While JavaScript helps you develop the website, AJAX will enhance your website’s performance and the overall UX. So, it’s quintessential to have an understanding of AJAX along with JavaScript. 

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