Chapter 8. Ajax Optimization

First described by Jesse James Garrett, [120] Asynchronous JavaScript and XML (Ajax) is a new way to boost the interactivity of websites.

Ajax [121] is a cross-platform set of technologies that allows developers to create web pages that behave more interactively, like applications. It uses a combination of Cascading Style Sheets (CSS), XHTML, JavaScript, and some textual data—usually XML or JavaScript Object Notation (JSON)—to exchange data asynchronously. This allows sectional page updates in response to user input, reducing server transfers (and resultant wait times) to a minimum. Properly coded, Ajax pages replace the old full-page paint, decide, click, and wait approach with streamlined partial page redraws, thereby boosting response times, interactivity, and usability.


The communications pattern now known as Ajax was developed before 2005. Web developers using DHTML, iframes, image-cookie communication systems, Java applets, and Flash had experimented with richer communication forms that resulted in a more desktop-like experience. Until it had the new moniker “Ajax,” however, the partial-page update pattern wasn’t commonly utilized by web developers. Maybe the time wasn’t right. Maybe large-scale examples were missing or maybe the terms Rich Internet Applications (RIAs), remote scripting, and inner browsing design failed to capture the imagination of the browsing public.

Ultimately, the goal of Ajax is to increase conversion rates through a faster, ...

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