ASP.NET 4 24-Hour Trainer

Chapter 24A. Using the AJAX Extensions in Web Forms

When a typical ASP.NET page needs to be refreshed from the server, it triggers a complete page refresh. The result is a slight delay and a flicker of the page. Wouldn't it be great if your page had the ability to submit only the section that needed to be updated, and it subsequently only needed to refresh that section? The AJAX Extensions in the ASP.NET Web Forms framework gives your web pages the ability to perform partial page updates. In this lesson I teach you how to use all of the controls included as part of the AJAX Extensions.

Ajax stands for Asynchronous JavaScript and XML. It enables your client-side web pages to exchange information with the server by using asynchronous calls. To do this, it uses both JavaScript and XML and can require a great deal of code. Because of the complexity involved in programming Ajax, a number of popular Ajax libraries have been developed. In fact, Microsoft includes an Ajax library as part of the ASP.NET 4 framework. The AJAX Extensions are server-side controls that use the Ajax library that is shipped with ASP.NET 4.

AJAX EXTENSIONS CONTROLS

The controls that are included in the AJAX Extensions are located in the AJAX Extensions tab of the Toolbox. Figure 24A-1 shows the list of AJAX Extensions.

Figure 24A.1. FIGURE 24A-1

This is information about each of the controls:

• ScriptManager — This control ...