Created By:Piyush Verma | Created Date :11 March, 2023
Ajax (AJAX short for "Asynchronous JavaScript and XML") is a set of web development techniques that use various web technologies on the client side to create asynchronous web applications. Ajax allows web applications to send and retrieve data from a server asynchronously (in the background) without affecting existing page display and behavior. By decoupling the data exchange layer from the presentation layer, Ajax allows websites, and therefore web applications, to dynamically change content without having to reload the entire page. In practice, modern implementations often use JSON instead of XML.
Ajax is not a technology, but a programming concept. HTML and CSS can be used in combination to mark up and format information. The web page can be modified by JavaScript to display dynamically and allow the user to interact with the new information.
In the early and mid 1990s, most websites were based on full HTML pages. A whole new page had to be loaded from the server for each user action. This process was inefficient, which was reflected in the user experience: all the content on the page disappeared, and then the new page appeared. Each time the browser reloaded a page due to a partial change, all of the content had to be resent, even though only part of the information had changed. This put an additional load on the server and made bandwidth a limiting factor for performance.
In 1996 Internet Explorer introduced the iframe tag; Just like the object element, it can load or retrieve content asynchronously. It appeared as XMLHTTP in the second version of the MSXML library shipped with Internet Explorer 5.0 in March 1999.
The XMLHTTP Windows ActiveX control feature in IE 5 was later implemented as an XMLHttpRequest JavaScript object by Mozilla Firefox, Safari, Opera, Google Chrome, and other browsers. Microsoft adopted the native XMLHttpRequest model starting with Internet Explorer 7. Internet Explorer still supports the ActiveX version, but not Microsoft Edge. The usefulness of these background HTTP requests and asynchronous web technologies remained largely obscure until they appeared in major online applications such as Outlook Web Access (2000) and Oddpost (2002).
Google made a broad cross-browser, standards-compliant implementation of Ajax with Gmail (2004) and Google Maps (2005). Kayak.com's public beta release in October 2004 was one of the first large-scale e-commerce applications of what developers called "the xml-http thing" at the time. This increased interest in Ajax among web developers.
On April 5, 2006, the World Wide Web Consortium (W3C) published the first draft specification for the XMLHttpRequest object to create an official web standard. The latest draft of the XMLHttpRequest object was released on October 6, 2016, and the XMLHttpRequest specification is now a living standard.
The term Ajax now stands for a broad group of web technologies that can be used to implement a web application that communicates with a server in the background without affecting the current state of the page. In the article that coined the term Ajax, Jesse James Garrett explained that the following technologies are built in:
The Document Object Model (DOM) for dynamically displaying and interacting with data
JSON or XML for data exchange and XSLT for XML manipulation
The XMLHttpRequest object for asynchronous communication
JavaScript to unify these technologies
However, since then there have been a number of developments in the technologies used in an Ajax application and in the definition of the term Ajax itself. XML is no longer required for data exchange and therefore XSLT is no longer required for data manipulation. JavaScript Object Notation (JSON) is often used as an alternative exchange format
