What is JavaScript Used For? By: Rachel Meltzer December 3, 2020 Estimated reading time: 3 minutes. Javascript is used by programmers across the world to create dynamic and interactive web content like applications and browsers. JavaScript is so popular that it's the most used programming language in the world, used as a client-side programming language by 97.0% of all websites. Client-side languages are those whose action takes place on the user's computer, rather than on the server. JavaScript is versatile enough to be used for a variety of different applications, like software, hardware controls, and servers. JavaScript is most known for being a web-based language, because it's native to the web browser. The web browser can naturally understand the language, like how a native English speaker can naturally understand English. JavaScript has evolved over the past 25 years to become a versatile and accessible programming language for working with web browsers. Developers use JavaScript to build complex interactive websites and browser games, and to connect servers to websites and web applications. Because of this versatility, it’s easy to see why this language is the most commonly used programming language in the world. Creating Interactive Websites JavaScript makes web pages dynamic. Before JavaScript, web pages were built only with HTML and CSS. HTML and CSS are only capable of creating static pages that can be styled but not interactive aside from hyperlinks. Some of the most popular websites are built with JavaScript, including Google, YouTube, and Facebook. JavaScript allows developers to implement features like: Showing and hiding menus or information Adding hover effects Creating image galleries in a carousel format Zooming in or zooming out on an image Playing audio or video on a web page Adding animations Creating drop down and hamburger-style menus Building Applications With JavaScript’s extensive collection of frameworks, developers can efficiently build apps for mobile and web. Frameworks are libraries of pre-written JavaScript code that developers use for standard features. You can think of a JavaScript framework like a blueprint. The most popular JavaScript application frameworks are: React: a collection of JavaScript created to build user interfaces for web applications. React Native: a collection that allows developers to build mobile apps with JavaScript. Node.js: a collection that enables two-way communications with servers for exchanging data. Facebook built React and React Native, which are currently powering some of the world’s most powerful social media applications. React is used by websites like Uber, Pinterest, Netflix, Instagram, Amazon, Twitter, Udemy, and more. Facebook, Instagram, Shopify, Words with Friends, Skype, Pinterest, Discord, Tesla, and Uber Eats use React Native. Developing Engaging Games JavaScript is frequently used to create in-browser games. Developers use JavaScript to create 2D and 3D puzzles, role-playing games, racing games, platform games, and more. Creating a simple browser game can be a great way to start practicing your JavaScript skills as a beginner. There are hundreds of JavaScript game engines that provide frameworks for buidling games, and many are free and open-source. The most popular game engines include Backbone, DarlingJS, and JawsJS. Popular browser-based games built using JavaScript: Angry Birds 2048 Little Alchemy Polycraft HexGL CrossCode Bejeweled Gods Will be Watching What is JavaScript Designed For? JavaScript was designed by Brendan Eich at Netscape as a way to remove the limitation of static pages on the web. Eich set out to create a scripting language for the web that used the syntax of Java, another programming language. JavaScript was designed for: Speed: it’s faster to execute code within a web browser in its native language than it is to execute code on the server. Dynamic pages: pages that users can interact with weren’t possible before JavaScript’s inception. Reducing memory use: executing the code in the browser helps free up space on servers, which helps cut costs. Building responsive user interfaces: almost all social media user interfaces rely on JavaScript. Reloading certain parts of the page independently: those suggestions when you start typing in Google’s search bar are all thanks to JavaScript. Responsive content: when you change your browser window’s size, JavaSCript lets the size of the content on the page change with it. Form validation: required fields are enforced by JavaScript, so that you don’t miss any information when you’re shopping online. Autocomplete: JavaScript helps save us from manually inputting our email address every time we fill out an online form. Playing audio and video: remember Flash? JavaScript’s audio and video capabilities are the reason it’s now obsolete. Later, HTML was updated to handle media files too, but JavaScript did it first. Why do we Need JavaScript? Whether you plan to specialize in front-end, back-end, or full-stack development, JavaScript is a crucial programming language for any web developer. Without JavaScript, we wouldn’t have the dynamic and interactive web pages that have become the standard user experience we all know, love, and rely on. Is JavaScript Used for Front-End or Back-End? Javascript is a client-side language, which technically makes it a front-end language. But with the Node.js framework, JavaScript can also be used in back-end. Using JavaScript across the whole stack, for both front-end and back-end, is an excellent practice because it creates a cohesive application. When as much code as possible is all in the same language, it makes it easier to maintain, manage, update, and build with a single team. When it’s used for front-end, JavaScript makes web pages dynamic and interactive. It validates submission forms, updates certain pieces of content on the page without updating the entire page, shows and hides menus, and displays animations. When it's used for back-end, the Node.js framework allows a server to handle front-end data updates and build scalable network applications to process simultaneous user requests. Want to learn more about the web's favourite programming language? Start to code with our free 10-hour online course, or go all-in and apply for our web development bootcamp.