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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
Languages
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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

Default parameters


Function parameters can be assigned default values. While calling the function, if a parameter is omitted, the default value assigned to the parameter is used:

    function render(fog_level=0, spark_level=100){ 
      console.log(`Fog Level: ${fog_level} and spark_level:
       ${spark_level}`) 
    } 
    render(10); //Fog Level: 10 and spark_level: 100 

In this example, we are omitting the spark_level parameter, and hence the default value assigned to the parameter is used. It is important to note that undefined is considered as an absence of parameter value; consider the following line of code, for example:

    render(undefined,10); //Fog Level: 0 and spark_level: 10 

While providing default values of parameters, it is possible to refer to other parameters as well:

    function t(fog_level=1, spark_level=fog_level){
      console.log(`Fog Level: ${fog_level} and spark_level: 
       ${spark_level}`) 
      //Fog Level: 10 and...
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