Book Image

Object-Oriented JavaScript - Third Edition

By : Stoyan STEFANOV, Antani
5 (1)
Book Image

Object-Oriented JavaScript - Third Edition

5 (1)
By: Stoyan STEFANOV, Antani

Overview of this book

JavaScript is an object-oriented programming language that is used for website development. Web pages developed today currently follow a paradigm that has three clearly distinguishable parts: content (HTML), presentation (CSS), and behavior (JavaScript). JavaScript is one important pillar in this paradigm, and is responsible for the running of the web pages. This book will take your JavaScript skills to a new level of sophistication and get you prepared for your journey through professional web development. Updated for ES6, this book covers everything you will need to unleash the power of object-oriented programming in JavaScript while building professional web applications. The book begins with the basics of object-oriented programming in JavaScript and then gradually progresses to cover functions, objects, and prototypes, and how these concepts can be used to make your programs cleaner, more maintainable, faster, and compatible with other programs/libraries. By the end of the book, you will have learned how to incorporate object-oriented programming in your web development workflow to build professional JavaScript applications.
Table of Contents (19 chapters)
15
B. Built-in Functions
17
D. Regular Expressions

Chapter 4, Objects

Lets solve the following exercises:

Exercises

  1. What happens here? What is this and what's o?
            function F() { 
              function C() { 
                return this; 
              } 
              return C(); 
            } 
            var o = new F(); 
    

    Here, this === window because C() was called without new.

    Also o === window because new F() returns the object returned by C(), which is this, and this is window.

    You can make the call to C() a constructor call:

            function F() { 
              function C() { 
                return this; 
              } 
              return new C(); 
            } 
            var o = new F(); 
    

    Here, this is the object created by the C() constructor. So is o:

            > o.constructor.name; 
            "C" 
    

    It becomes more interesting with ES5's strict mode. In the strict mode, non-constructor invocations result in this being undefined, not the global object. With "use strict" inside F() or C() constructor's body, this would be undefined...