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What Do JavaScript Developers Do?

As one of the most in-demand IT skills for 2020, JavaScript developers work a major role in software development.

Emma White

By Emma White

Business Development Manager Emma White helps BairesDev grow at a global level by expanding the client base and overseeing of growth projects.

10 min read

JavaScript Developers Do

Developers use various programming languages to turn visions and plans into functional, appealing websites and applications. JavaScript is central to this process, as it’s used to create responsive, interactive web page elements that significantly improve user experience. It’s so effective that over 95% of websites use it to enable dynamic content.

Given the pivotal role of JavaScript in front-end web development, businesses seek out developers with expertise in this language at a high rate. According to a report from DevSkiller, a developer skills tester, JavaScript is the most in-demand IT skill for 2020 and approximately 72% of companies are looking for JavaScript developers.

What exactly do these in-demand developers do, working at JavaScript development companies like BairesDev? After first distinguishing it from the similarly named Java, we’ll explore the various uses and end products associated with this versatile programming language.

Java vs. JavaScript

Despite the similar names, JavaScript is not the same as Java. Java, currently the third most popular programming language after JavaScript and Python, runs on over one billion devices as part of Google’s Android operating system. Released by Sun Microsystems in 1995, Java is now owned by Oracle. It’s commonly used for credit card programming, Android apps, desktop apps, and enterprise-level apps.

JavaScript was created by a developer at Netscape in the early 1990s. It started as a programming language that could direct a computer to interpret user commands without the need for plug-ins or compiling code. The language was first called “LiveScript” and added to Netscape Navigator. It was later renamed “JavaScript” to take advantage of the growing popularity of Java at the time.


  • Both are object-oriented languages that use “objects” to represent data and methods, as opposed to procedural programming with a list of instructions.
  • Both can be used in front-end development and on the server side.


  • The languages are assembled, written, and executed differently.
  • JavaScript is all text code, while Java code must be compiled.
  • JavaScript is weakly typed (variables aren’t bound to a specific data type), while Java is strongly typed (requiring developers to define code variables with data type restrictions).
  • The languages use different plug-ins.
  • JavaScript runs on a browser only, while Java creates apps that run on a Java virtual machine or a browser.
  • JavaScript is more involved on the client side, while Java is typically used for server-side functionality.

Front-End Web Development

Front-end web developers use JavaScript, in combination with HTML and CSS, to build the visible parts of websites and apps that users interact with on a phone, tablet, or computer.

Hypertext markup language (HTML) is used to format and arrange web pages. It’s responsible for the structure of the website and allows content in the form of text, images, links, and videos. CSS is used to style the content that HTML inserts on web pages. It sets shapes, sizes, colors, and fonts, controlling how the web page appears.

JavaScript is the scripting language that developers use to create and control dynamic content, and turn web elements into interactive features. It is involved with anything that refreshes on its own, such as interactive forms, autocomplete features and animated menus, and it enables new content to load automatically as users scroll through a site.

Additional capabilities produced by JavaScript include:

  • Forms with error checking input fields to ensure users enter correct and complete information in all necessary fields
  • Animated images
  • Personalized greetings based on time of day
  • Interactive maps

JavaScript developers can add a wide range of useful functionality to websites, as described in the following video:

Back-End Web Development and Other Uses

While JavaScript is primarily involved in front-end web development, it does have other uses. Developers use some forms of JavaScript, such as Node JS, in back-end development. In this case, it builds and maintains the infrastructure that allows websites and apps to function.

Node JS is an open-source runtime environment that processes server-side code and helps to execute a program. It increases speeds by using server idle time and an event loop to complete requests.

JavaScript is also part of Android and iOS systems, Desktop, and Hybrid. These uses are possible because JavaScript engines — interpreters that convert JavaScript code into machine code that a CPU can execute — are written in C++ and can be embedded into any C++ application.

Additional End Products

While the primary product of JavaScript is interactive, dynamic web sites, developers also use it in other aspects of web development and to create games, mobile and web apps, web servers, and web-based slide presentations.

Web development

In addition to front-end development features such as interactive forms and animation, JavaScript enables users to load content to a website without having to reload the whole page. It also supports external web applications like Flash, PDF, and widgets.


Developers can use JavaScript with HTML5 to create interactive games with complex graphics and animation that only require a keyboard to play. Libraries, like Ease JS, offer solutions for working with game graphics and allow developers to integrate several images into one, reducing server requests and bandwidth requirements. These actions speed up gameplay.

Mobile apps

Developers can use JavaScript to create cross-platform mobile apps for iOS, Android, Windows, and Blackberry that load content quickly and support a range of display sizes and screen resolutions. Frameworks, like React Native, that enable this functionality are typically open-sourced and served by support communities that provide documentation and resources to assist developers.

Web apps

Since JavaScript can interact directly with browsers rather than sending messages via servers, it allows developers to build faster web applications. When developers use application programming interfaces (APIs) with JavaScript, they add functionality and performance. With APIs, apps only request the specific data that’s needed, avoiding the storage of unnecessary fields.

Web servers

Developers can use JavaScript to create web servers using the Node JS framework. This approach is event-driven, so this type of web server is very fast when moving on to the next task without transferring large amounts of data. Commands are executed individually in single-threaded processes, which reduces the number of errors.

Web-based slide presentations

Developers can use JS libraries, like Reveal JS and Bespoke JS to create interactive web-based slideshow presentations. Users can add images and elements like bulleted lists, and sliding decks provide responsive scaling to adapt to desktop, mobile device, and tablet use.

JavaScript Developers are in High Demand

It’s not surprising that JavaScript developers are in such high demand, given that businesses and individuals have come to expect the responsive and interactive web page elements that this language makes possible. The need for this level of interactivity is likely to continue, so it’s likely the demand for JavaScript developers won’t diminish anytime soon.

Emma White

By Emma White

Emma White is a Business Development Manager at BairesDev with a background in tech company expansion through client base growth. White helps to expand BairesDev's business at a global scale while managing new market research, overseeing growth projects, and generating leads.

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