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Learning JavaScript Data Structures and Algorithms - Third Edition
book

Learning JavaScript Data Structures and Algorithms - Third Edition

by Loiane Avancini
April 2018
Beginner to intermediate content levelBeginner to intermediate
426 pages
10h 19m
English
Packt Publishing
Content preview from Learning JavaScript Data Structures and Algorithms - Third Edition

Using map and filter

JavaScript also has two other iterator methods that return a new array with a result. The first one is the map method, which is as follows:

const myMap = numbers.map(isEven); 

The myMap array will have the following values: [false, true, false, true, false, true, false, true, false, true, false, true, false, true, false]. It stores the result of the isEven function that was passed to the map method. This way, we can easily know whether a number is even or not. For example, myMap[0] returns false because 1 is not even, and myMap[1] returns true because 2 is even.

We also have the filter method. It returns a new array with the elements for which the function returned true, as follows:

const evenNumbers = numbers.filter(isEven); ...
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Learning JavaScript Data Structures and Algorithms

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Publisher Resources

ISBN: 9781788623872Supplemental Content