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Object-Oriented JavaScript

You're reading from   Object-Oriented JavaScript Learn everything you need to know about object-oriented JavaScript (OOJS)

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Product type Paperback
Published in Jan 2017
Publisher Packt
ISBN-13 9781785880568
Length 550 pages
Edition 3rd Edition
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Authors (2):
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Stoyan STEFANOV Stoyan STEFANOV
Author Profile Icon Stoyan STEFANOV
Stoyan STEFANOV
Ved Antani Ved Antani
Author Profile Icon Ved Antani
Ved Antani
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Toc

Table of Contents (19) Chapters Close

Preface 1. Object-Oriented JavaScript FREE CHAPTER 2. Primitive Data Types, Arrays, Loops, and Conditions 3. Functions 4. Objects 5. ES6 Iterators and Generators 6. Prototype 7. Inheritance 8. Classes and Modules 9. Promises and Proxies 10. The Browser Environment 11. Coding and Design Patterns 12. Testing and Debugging 13. Reactive Programming and React A. Reserved Words B. Built-in Functions
C. Built-in Objects D. Regular Expressions
E. Answers to Exercise Questions

String

The String() constructor creates string objects. Primitive strings are turned into objects behind the scenes if you call a method on them as if they were objects. Omitting new gives you primitive strings.

Creating a string object and a string primitive:

    > var s_obj = new String('potatoes');  
    > var s_prim = 'potatoes'; 
    > typeof s_obj; 
    "object" 
    > typeof s_prim; 
    "string" 

The object and the primitive are not equal when compared by type with ===, but they are when compared with == which does type coercion:

    > s_obj === s_prim; 
    false 
    > s_obj == s_prim; 
    true 

length is a property of the string objects:

    > s_obj.length; 
    8 

If you access length on a primitive string, the primitive is converted to an object behind the scenes and the operation is successful:

    > s_prim.length; 
    8 

String literals work fine too:

    > "giraffe".length; 
        7

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