Professional ASP.NET 3.5 AJAX

11.1. Building Client-Side ASP.NET AJAX Controls

JavaScript files can be written using several different techniques. A great majority of scripts on the Internet consist of multiple functions thrown into one or more files used to perform client-side functionality. While these types of unstructured scripts certainly get the job done, they don't encapsulate related functions into containers for better code reuse and organization. Relatively few scripts rely on object-oriented techniques where JavaScript classes are defined using the JavaScript function and prototype design pattern.

Although JavaScript is not a true object-oriented language, it is capable of emulating several object-oriented characteristics that can be used to build new types, extend existing types, and in general create a reusable client-side object library. Building custom AJAX controls requires understanding how to leverage encapsulation features built into the JavaScript language that can be used to create classes. It also requires an understanding of how the ASP.NET AJAX script library extends JavaScript's default set of features.

Terminology between JavaScript and VB.NET or C# objects is surprisingly similar. Functionality can be grouped into classes, although JavaScript doesn't technically support the concept of a class and doesn't use the class keyword. However, JavaScript does support organizing related functionality into container objects much like VB.NET and C# do. Both JavaScript and .NET "classes" can ...