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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

Functions are data


Functions in JavaScript are actually data. This is an important concept that we'll need later on. This means that you can create a function and assign it to a variable, as follows:

    var f = function () { 
      return 1; 
    }; 

This way of defining a function is sometimes referred to as function literal notation.

The function () { return 1;} part is a function expression. A function expression can optionally have a name, in which case it becomes a named function expression (NFE). So, this is also allowed, although rarely seen in practice (and causes IE to mistakenly create two variables in the enclosing scope-f and myFunc):

    var f = function myFunc() { 
      return 1; 
    }; 

As you can see, there's no difference between a named function expression and a function declaration. But they are, in fact, different. The only way to distinguish between the two is to look at the context in which they are used. Function declarations may only...

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