Ajax is only a name given to a set of tools that were previously existing. The main part is XMLHttpRequest, a server-side object usable in JavaScript , that was implemented into Internet Explorer since the 4.0 version. It is in Internet Explorer an ActiveX object that was first named XMLHTTP some times, before to be generalized on all browser under the name XMLHttpRequest, when the Ajax technologie becomes commonly used. The use of XMLHttpRequest in 2005 by Google, in Gmail and GoogleMaps has contributed to the success of this format. But this is the name Ajax itself that made the technology so popular. Why to use Ajax? Mainly to build a fast, dynamic website, but also to save resources. For improving sharing of resources, it is better to use the power of all the client computers rather than just an unique server and network. Ajax allows to perform processing on client computer (in JavaScript) with data taken from the server. The processing of web page formerly was only server-side, using web services or PHP scripts, before the whole page was sent within the network. But Ajax can selectively modify a part of a page displayed by the browser, and update it without the need to reload the whole document with all images, menus, etc… For example, fields of forms, choices of user, may be processed and the result displayed immediately into the same page. What is Ajax in depth? Ajax is a set of technologies, supported by a web browser, including these elements: ? HTML and CSS for presenting. ? JavaScript (ECMAScript) for local processing, and DOM (Document Object Model) to access data inside the page or to access elements of XML file read on the server (with the getElementByTagName method for example) ? The XMLHttpRequest class read or send data on the server asynchronously. optionally… ? The DomParser class may be used ? PHP or another scripting language may be used on the server…
Download Ajax Tutorial (Asynchronous Javascript And XML).Pdf
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