What is JavaScript Used For?

The 14th annual Stack Overflow Developer Survey dropped yesterday. The findings about AI use and remote work are highly specific to the 2024 tech landscape. But there’s one data point that remains consistent year after year: JavaScript is once again the most popular programming language. The language’s popularity and staying power stems largely from its versatility.

While originally designed for front-end development, JavaScript’s extensive list of associated libraries and frameworks have extended its utility. Now, you can use it for just about anything — including back-end, mobile, and game development. Below, we’ll delve into the reasons behind the language’s popularity and its many applications.

If you’d prefer to get right into and start learning how to code with JavaScript, check out our Learn JavaScript course.

What is JavaScript?

JavaScript is a programming language that enables dynamic interactions on websites. It’s a cornerstone technology of the web, alongside HTML and CSS, and is essential for creating interactive web applications. Beginners often start with HTML, CSS, and JavaScript to master the basics of web development. Read through the profiles of Codecademy learners and you’ll notice that most of them choose JavaScript as their first language.

Why is JavaScript so popular?

When it was first developed in 1995, JavaScript was intended to be a lightweight language used to make web pages more dynamic. It added simple effects, like showing and hiding elements with the click of a button — but it wasn’t long before developers realized that it could do much more.

In time, JavaScript became one of the few languages that could be used in just about every web browser. Today, most of those other languages have fallen by the wayside, leaving JavaScript as the only programming language that can be used in every popular browser.

The next big break for JavaScript came when developers started experimenting with it outside of web browsers. They applied it to the back end of web servers, where it processed the data used by the front end. After the rise of smartphones, it found use in multiple mobile development tools that create apps that run on both the Android and iOS platforms.

Fun fact: Codecademy learners spent the most time taking our JavaScript courses last year, making it the favorite language in the bunch. In another article, we explore more of the reasons behind Javascript’s popularity.

What is JavaScript used for?

JavaScript is used in every industry to create all types of applications. Let’s take a closer look at its uses in web development, mobile development, game development, and more.

Front-end web development

Front-end developers use JavaScript (along with HTML and CSS) to create the parts of a web page that users see and interact with in their browsers.

Before JavaScript, web pages only served static content. JavaScript gave developers the ability to provide their users with a dynamic web experience, adding animations and other interactive elements. When you click a button on a website, and a side panel opens or a modal slowly comes into view, that’s JavaScript at work.

But JavaScript does more than that on the web. You can also use it to create single-page applications (or SPAs) that run on one HTML page to give users a smooth navigational experience.

Back-end web development

JavaScript is also popular with back-end developers. Back-end web development (also known as server-side development) involves creating the code that runs on a web server. When a browser loads a web page, it makes a call to a remote server. Server-side code then parses the page’s URL to determine what the user is requesting before retrieving and transforming the required data to serve back to the browser.

Node.js is a JavaScript framework commonly used for back-end development — so much so that many back-end JavaScript developers refer to themselves as Node.js developers.

Wanna try it for yourself? Take your first steps into back-end development by learning how to create a back-end app with JavaScript.

Game development

You can also use JavaScript to create 2D and 3D video games that run in web browsers. As browsers get more powerful, web-based video games are evolving beyond simple platformers. Now, JavaScript frameworks like Phaser.js allow you to create more advanced games quickly and easily right from your browser.

Mobile development

For years, mobile developers had to commit themselves to either Android or iOS, as each platform uses different programming languages. Android developers would learn Java or Kotlin, while iOS devs preferred Swift or Objective-C.

Now, with the rise of mobile development frameworks like React Native and Ionic, you can use JavaScript to create apps that run on both platforms.

Virtual reality (VR)

Virtual reality is a thing again, as devices like the Oculus Rift and Valve Index have made it more generally accessible. Now, you can use JavaScript to create applications for both of them.

A-Frame is a popular JavaScript framework used to build virtual reality experiences in web browsers. If you’re interested in building your own VR applications, start by Learning A-Frame.

Artificial intelligence (AI)

JavaScript is also used to develop artificial intelligence, as libraries like TensorFlow bring the power of machine learning to JavaScript developers. Developers can use these libraries to create machine learning models that predict future events based on past data and categorize data and images.

How long does it take to learn JavaScript

There’s no hard and fast answer to how long it takes to learn a language, in part because you’re never really finished learning. Like other languages, learning JavaScript can take a few months to a year. All Codecademy courses and paths are crafted for self-guided learning, giving you the power to set a pace and schedule that fits your needs. Typically, we suggest investing anywhere from five to 15 hours each week in coding if you want to make a quick career change — though remember, everyone’s goals, lives, and schedules are unique.

JavaScript code examples

Here’s a simple JavaScript snippet that demonstrates basic syntax, including variable declaration, a function, and a loop:

// Declare a variable
let message = "Hello, world!";

// Function to display the message
function showMessage(msg) {
  console.log(msg);
}

// Call the function with the variable as an argument
showMessage(message);

// Loop to display numbers from 1 to 5
for (let i = 1; i <= 5; i++) {
  console.log("Number: " + i);
}

Learn more about JavaScript

JavaScript is no longer just a programming language used to create neat effects in web browsers. It’s a well-respected, powerful language that’s climbed to the top of popularity charts over the past three decades.

JavaScript’s versatility and wide range of applications make it a valuable addition to any developer’s tech stack.Ready to start using it yourself? Learn its basics in our introduction to JavaScript. Or, if you’re looking for something more advanced, check out our full list of JavaScript courses and tutorials.

This blog was originally published in May 2021 and has been updated to include new data points, courses, and details about JavaScript.