Book Image

Learning JavaScript Data Structures and Algorithms - Second Edition

By : Loiane Groner
Book Image

Learning JavaScript Data Structures and Algorithms - Second Edition

By: Loiane Groner

Overview of this book

This book begins by covering basics of the JavaScript language and introducing ECMAScript 7, before gradually moving on to the current implementations of ECMAScript 6. You will gain an in-depth knowledge of how hash tables and set data structure functions, as well as how trees and hash maps can be used to search files in a HD or represent a database. This book is an accessible route deeper into JavaScript. Graphs being one of the most complex data structures you’ll encounter, we’ll also give you a better understanding of why and how graphs are largely used in GPS navigation systems in social networks. Toward the end of the book, you’ll discover how all the theories presented by this book can be applied in real-world solutions while working on your own computer networks and Facebook searches.
Table of Contents (18 chapters)
Learning JavaScript Data Structures and Algorithms - Second Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface

The ES6 WeakMap and WeakSet classes


Along with the two new data structures Set and Map, ES6 also introduced a weak type version of these classes: WeakMap and WeakSet.

Basically, the only difference between the Map or Set classes and their Weak versions are:

  • The WeakSet or WeakMap classes do not have the entries, keys, and values methods

  • It is only possible to use 0bjects as a key

The reason for creating and using these two classes is performance related. As WeakSet and WeakMap are weakly typed (using object as a key), there is no strong reference to the keys. This behavior allows the JavaScript garbage collector to clean an entire entry from the map or set.

Another advantage is that you can only retrieve a value if you have its key. As these classes do not have the iterator methods (entries, keys, and values), there is no way to retrieve a value unless you know what the key is. This confirms our choice in using the WeakMap class to encapsulate the private properties of the ES6 classes, as you...