Book Image

Mastering Immutable.js

By : Adam Boduch
Book Image

Mastering Immutable.js

By: Adam Boduch

Overview of this book

Immutable.js is a JavaScript library that will improve the robustness and dependability of your larger JavaScript projects. All aspects of the Immutable.js framework are covered in this book, and common JavaScript situations are examined in a hands-on way so that you gain practical experience using Immutable.js that you can apply across your own JavaScript projects. The key to building robust JavaScript applications using immutability is to control how data flows through your application, and how the side-effects of these flows are managed. Many problems that are difficult to pinpoint in large codebases stem from data that’s been mutated where it shouldn’t have been. With immutable data, you rule out an entire class of bugs. Mastering Immutable.js takes a practical, hands-on approach throughout, and shows you the ins and outs of the Immutable.js framework so that you can confidently build successful and dependable JavaScript projects.
Table of Contents (23 chapters)
Title Page
Credits
About the Author
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface

Sorting maps


Just like lists, maps can be sorted too. To preserve the new order of the map once it's sorted, you have to convert it to an ordered map. You can also sort maps by their keys.

Creating ordered maps

Maps have a sort() method, just like lists. They even use the same default comparator function. To preserve the order of the map after sort() has been called, you can use toOrderedMap() to convert it, as follows:

const myMap = Map.of(
  'three', 3,
  'one', 1,
  'four', 4,
  'two', 2
);
const mySortedMap = myMap
  .toOrderedMap()
  .sort();

myMap.forEach(
  (v, k) => console.log('myMap', `${k} => ${v}`)
);
// -> myMap three => 3
// -> myMap one => 1
// -> myMap four => 4
// -> myMap two => 2

mySortedMap.forEach(
  (v, k) => console.log('mySortedMap', `${k} => ${v}`)
);
// -> mySortedMap one => 1
// -> mySortedMap two => 2
// -> mySortedMap three => 3
// -> mySortedMap four => 4

The semantics of sort() are the same for lists...