Introduction


AJAX = Asynchronous JavaScript and XML.

AJAX is a web technology for creating fast and dynamic web pages.

AJAX allows web pages to be updated asynchronously by exchanging small amounts of data without refreshing the whole page. This means that it is possible to update parts of a web page, without reloading the whole page.

Web pages that do not use AJAX must reload the entire page if the content change.

Examples of applications using AJAX: Google Maps, Gmail, YouTube, and Facebook tabs.

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  1. Web browser requests for the content of just the part of the page that it needs.
  2. Web server analyzes the received request and builds up an XML message which is then sent back to the Web browser.
  3. After the Web browser receives the XML message, it parses the message in order to update the content of that part of the page.

AJAX is based on Internet Standards

AJAX is based on internet standards, and uses a combination of:

XMLHttpRequest object (to exchange data asynchronously with a server)

JavaScript/DOM (to display/interact with the information)

CSS (to style the data)

XML (often used as the format for transferring data)