Skip to Content
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

let and const instead of var

Until ES5, we could declare variables in any place in our code, even if we overwrote the variables declaration, as in the following code:

var framework = 'Angular'; 
var framework = 'React'; 
console.log(framework); 

The output of the preceding code is React, as the last variable declared, named framework, was assigned this value. In the previous code, we had two variables with the same name; this is very dangerous and might drive the code to an incorrect output.

Other languages, such as C, Java, and C#, do not allow this behavior. With ES2015, a new keyword was introduced, called let. let is the new var keyword, meaning we can simply substitute the keyword var for let. In the following code, we have an example: ...

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Start your free trial

You might also like

Learning JavaScript Data Structures and Algorithms

Learning JavaScript Data Structures and Algorithms

Loiane Avancini

Publisher Resources

ISBN: 9781788623872Supplemental Content