In this chapter, you’ll learn about OOP (Object-Oriented Programming) and how it relates to JavaScript. As an ASP.NET developer, you probably have some experience working with objects, and you may even be familiar with concepts such as inheritance. However, unless you’re already an experienced JavaScript programmer, you probably aren’t familiar with the way JavaScript objects and functions really work. This knowledge is necessary in order to understand how the Microsoft AJAX Library works, and this chapter will teach you the necessary foundations. More specifically, you will learn:

What encapsulation, inheritance, and polymorphism mean
How JavaScript functions work
How to use anonymous functions and closures
How to read a class diagram, and implement it using JavaScript code
How to work with JavaScript prototypes
How the execution context and scope affect the output of JavaScript functions
How to implement inheritance using closures and prototypes
What JSON is, and what a JSON structure looks like
In the next chapters you’ll use this theory to work effectively with the Microsoft AJAX Library.

Concepts of Object-Oriented Programming
Most ASP.NET developers are familiar with the fundamental OOP principles because this knowledge is important when developing for the .NET development. Similarly, to develop client-side code using the Microsoft AJAX Library, you need to be familiar with JavaScript’s OOP features. Although not particularly difficult, understanding these features can be a bit challenging at first, because JavaScript’s OOP model is different than that of languages such as C#, VB.NET, C++, or Java.

source: c-sharpcorner.com
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