WEBDEV Concepts

24 Part 1: Internet: basic concepts AJAX technology The AJAX technology is available natively in WEBDEV. What is AJAX and what are its advantages? AJAX (Asynchronous JavaScript and XML) is used to refresh the data modified in an HTML page without having to redisplay the entire page. For example, if some elements in the page displayed (content of the cart, characteristics of a product, list of cities, map, etc.) are modified, only these elements will be refreshed. The server will not have to send the entire page to the user’s computer. This technology has several advantages: • fewer requests are made to the server. Therefore, it can support a larger number of simultaneous connections. • the information that circulates is less bulky. • the transmission time is shorted. • the user sees information immediately and without undesired visual effects. AJAX can be used at two different levels in a WEBDEV site: • Automatic AJAX: a simple click allows you to access the AJAX features. The code remains the same. • AJAX programming: AJAX-specific functions allow you to write complex processes. Remark : Only sufficiently recent browsers support AJAX technology. AJAXAvailable is used to determine if the current browser supports AJAX technology. If a process that is using the AJAX technology is run on a browser that does not support this technology, the process is run "as if" it did not use the AJAX technology (the entire page is refreshed for example).