Explanation:
What is AJAX and Microsoft AJAX Library?
AJAX stands for Asynchronous JavaScript and XML. JavaScript, though, is a simple programming language whose foundation was laid out quite a few years ago when object-oriented programming was considered overkill for Web pages. At the same time, principles of dynamic languages were considered too academic to be fully implemented in a broadly used programming language.
JavaScript is actually the client side implementation. It is primarily used to embed functions in HTML pages that glue together a user's actions with elements in the page. Document Object Model (DOM) is the schema for the controls or elements in the page—buttons, textboxes, and so on. With JavaScript, you can programmatically rename, edit, add, or delete elements in the displayed document and handle any events fired by such elements. In addition, you can perform any browser-specific action, such as opening or popping up a new window or—what makes AJAX so special—invoke the popular XMLHttpRequest object and place asynchronous calls to a remote URL.
JavaScript is the minimal required language for programmers who want to fix some actions in the web page but as whole it is not a sophisticated language which supports classes, Inheritance and interfaces.
AJAX on the other hand manipulates the XMLHttpRequest object and creates connection between a client and the data and objects lying on the server side. The main idea after AJAX is to decrease the traffic of unwanted data which also saves the time and improves the user internet browsing experience.
Introducing the Microsoft AJAX Library
The Microsoft AJAX Library itself is self-contained, written in JavaScript, and stored in a couple of .js files. This means that any programming environment that accepts JavaScript can successfully use the Microsoft AJAX Library provided that the constituent files are properly referenced. There are two main files involved in the Microsoft AJAX Library: MicrosoftAjax.js and MicrosoftAjaxWebForms.js. MicrosoftAjax.js defines language extensions supported by the Microsoft AJAX Library including namespaces, interfaces, enums, and inheritance. MicrosoftAjaxWebForms.js defines the partial rendering engine and the whole network stack.
In an ASP.NET AJAX application, you don't need to reference or embed any of these two files directly. This is one of the tasks that the ScriptManager control accomplishes for you:
Placed in an ASP.NET AJAX page, the preceding code guarantees that one or both of the Microsoft AJAX Library .js files will be downloaded to the client. If you're going to extend the capabilities of the browser's JavaScript in the context of a non-ASP.NET AJAX application, then you are going to have to reference any required .js files explicitly:
The source code of the Microsoft AJAX Library is located at ajax.asp.net/downloads. You can modify these scripts in your own pages.
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