JavaScript is a very powerful language. It is the most popular language in the world and is one of the most prominent languages on the Internet. For example, GitHub (the world's largest code host, available at https://github.com) hosts over 400,000 JavaScript repositories (the largest number of projects is in JavaScript; refer to http://goo.gl/ZFx6mg). The number of projects in JavaScript in GitHub grows every year.

JavaScript is not a language that can only be used in the frontend. It can also be used in the backend as well, and Node.js is the technology responsible for this. The number of Node Packages Modules (https://www.npmjs.org/) also grows exponentially.

JavaScript is a must-have on your résumé if you are or going to become a web developer.

In this book, you are going to learn about the most used data structures and algorithms. But why use JavaScript to learn about data structures and algorithms? We have already answered this question. JavaScript is very popular, and JavaScript is appropriate to learn about data structures because it is a functional language. Also, this can be a very fun way of learning something new, as it is very different (and easier) than learning about data structures with a standard language such as C or Java. And who said data structures and algorithms were only made for languages such as C and Java? You might need to implement some of these languages while developing for the frontend as well.

Learning about data structures and algorithms is very important. The first reason is because data structures and algorithms can solve the most common problems efficiently. This will make a difference on the quality of the source code you write in the future (including performance—if you choose the incorrect data structure or algorithm depending on the scenario, you can have some performance issues). Secondly, algorithms are studied in college together with introductory concepts of Computer Science. And thirdly, if you are planning to get a job in the greatest IT (Information Technology) companies (such as Google, Amazon, Ebay, and so on), data structures and algorithms are subjects of interview questions.