The ASP.NET AJAX Library brings familiar aspects of programming with the .NET Framework to JavaScript. You can create namespaces to group functionality. The AJAX Library provides a framework for using object-oriented development patterns from JavaScript. You can define interfaces and classes that implement them. You can extend types and call on the base implementation. The ASP.NET AJAX Library provides a set of exceptions in the Error class that work with the JavaScript Error object and provide a natural way to find and report problems. There is also debug support with verbose error messages to help you find bugs.
The AJAX Library also includes information about the browser object so that you can reliably customize your actions for the user’s environment. It also provides classes that assist in debugging. When running with debugging enabled, the ASP.NET AJAX Library will validate parameters passed to the framework classes and help you avoid errors.
The ASP.NET AJAX Library helps you to write JavaScript code in a familiar and intuitive way. Transitioning between VB.NET or C# and JavaScript is easier. You get a set of base class libraries that function in the browser the same way you see them work on the server. You get help working with strings and data that perform with high performance. The ASP.NET AJAX Library will also aid you in localizing your output for the application user.
Fundamentally, the ASP.NET AJAX Library is focused on making JavaScript programming easier. You can take advantage of ASP.NET on the server and leverage JavaScript in the browser. Although the languages you are using on client and server are different, you get a familiar set of functionaltiy that makes the transition back and forth easier.