Java vs. JavaScript: What's the Difference?

Though Java and JavaScript share half of a name, the two are far from the same—Java is a versatile programming language, while JavaScript helps create interactive web pages. In fact, according to Statista, JavaScript is the number one most popular programming language among developers worldwide, with Java ranking in seventh place in 2024 [1]. When looking at Java versus JavaScript syntax, you can see they look pretty different on the surface, and the differences go much deeper than that.

To compare and contrast the two languages, take a look at the history, features, uses, advantages, and disadvantages of Java and JavaScript, along with their similarities and differences.

What is the difference between Java and JavaScript?

When considering Java versus JavaScript, you’ll notice a few key differences. Java is a compiled language, meaning that you write code, then run it through a compiler and create bytecode. Then you run bytecode in a Java Virtual Machine (JVM), which is likely the software you have on your computer. JavaScript is an interpreted language. It doesn’t get compiled but is interpreted as the script runs. It's commonly used to create interactive websites. You’re reading this right now on a page running JavaScript.

What is Java?

Java launched with a “Write once, run anywhere” promise. Since then, it has quickly become very popular for creating client and server-side applications. It has a similar syntax to C and C++, but the two languages aren’t interchangeable. Despite similarities in syntax, many people consider Java easier to understand with fewer low-level features because that functionality is handled automatically by the compiler and JVM.

Features of Java

Java has been around for some time and has, as such, developed a large community with a host of tools and educational content related to the language.

It’s on par or faster than most other modern compiled languages and much faster than interpreted languages, making it a good choice for robust native applications. Unlike JavaScript, Java is a multi-threaded language, meaning it can do multiple things simultaneously rather than wait for each task to finish before beginning the next one.

Java is very secure. It has private methods and variables built in to avoid unauthorized access to the underlying data and functionality. Additionally, the compiled app runs in a virtual machine which keeps itself separate from the underlying device it is running on.

What is Java used for?

You can create almost any desktop application, mobile application, game, website backend, or server using Java, and it can even run machines. Wikipedia uses Java to execute its queries when you search on its website or app, and it even controls the systems in Mars rovers. Netflix, Google, Twitter, and several other big-name tech companies all use Java in some form to provide their services. 

Advantages of Java

Many reasons exist why Java is one of the most widely used programming languages. Designed to be easy to use, Java is simpler to write and makes it easier to compile, debug, and learn than other languages. It’s also an object-oriented programming language, meaning you can create modular programs and reusable code. One of Java’s most significant advantages is that it’s platform-independent. It’s able to move easily from one computer system to another.

Java is a robust language. Because it’s easy to use, platform independent, and has security features, it has become the language of choice for building the Internet of Things.

Disadvantages of Java

Though Java touts many excellent qualities, it lacks in performance. Java tends to run more slowly than languages like C and C++ and consumes a significant amount of memory. That extra memory requires more hardware to keep things running. More hardware means more money spent. Lastly, it offers virtually no support for low-level programming. 

History of Java

James Gosling began developing Java in 1991 for use with interactive television but was too advanced for cable at the time. Initially named Oak and then Green, it was finally given its official name of Java, after the type of coffee. The release of version 1.0 occurred in 1996 under Sun Microsystems and became one of the most ubiquitously used technologies in the world. It is the foundation of the Android operating system and the language of the popular video game Minecraft.

What is JavaScript, and is Java the same as JavaScript?

JavaScript is a programming language specifically created for web development. JavaScript has no direct relation to Java besides being used for web technologies. The name choice was a marketing move to encourage adoption.

Features of JavaScript

JavaScript has critical features that led to its widespread adoption. It runs live in the browser without having to compile beforehand, a process called just-in-time compilation. Every major web browser uses the language. It is responsible for many of the interactions you see on websites, like fetching new data without reloading the page, animations, checking forms for errors, chatting, posting comments, and much more.

What is JavaScript used for?

JavaScript is popular for web design, as it can turn a static brochure-style website into a functioning application that lives in your web browser. In fact, 98.9 percent of all websites use JavaScript as of December 2024, according to W3Techs [2]. With over 1.98 billion websites on the internet—a number that grows every day—that’s a lot of JavaScript [3]. 

It’s not only for the front end, though. JavaScript can run in Node environments, allowing you to write JavaScript for the back end. It can perform routing, controller functions, an API service, or all of those things at once. Node enables you to have a full JavaScript stack.

You can also make games in JavaScript. It is particularly suited for mobile and browser games, meaning you can make games for almost any device with a web browser. 

Advantages of JavaScript

The ability to run in a browser is a massive advantage for JavaScript. It’s one of the reasons that it has been the more popular language used in GitHub projects for several years in a row. Web browsers exist on a wide array of devices. All desktop computers, laptops, tablets, and smartphones have browsers, and many game consoles and smart TVs also have browsers.

When considering Java versus JavaScript for web development, JavaScript’s extreme versatility makes it an excellent choice. Being a full-stack engineer no longer means you must learn multiple languages. As a full-stack developer, you have to know an array of ideas, patterns, and paradigms, but you only need one syntax to bring all of it together.

Because of its popularity and pervasiveness, there’s an abundance of educational material about JavaScript. You can find books, videos, courses, articles, and podcasts on just about every facet of the technology. It’s not difficult to find someone with the information you need to accomplish your goal.

Disadvantages of JavaScript

Even though every modern browser runs JavaScript, different browsers can sometimes behave a bit differently. Browsers have code that interprets the JavaScript at runtime called engines. Chrome and Brave, for example, use the V8 engine, while Firefox uses the SpiderMonkey engine. These engines often interpret the code in the same way, but you’ll likely experience instances where the behavior is different than you might expect. The good news is that you can typically find a workaround for consistent behavior and plenty of resources documenting the flaws and how to fix them.

Some may say that JavaScript's dependence on the browser is a flaw. While the statement is somewhat true, as mentioned, it can now run in different environments with Node. With tools like React Native, you can create stand-alone apps that run on the most popular environments, like Windows, Mac OS, iOS, and Android. There’s a learning curve you should be aware of, though.

Speed is another factor to consider. Programming languages are technically just doing complicated math very, very quickly. JavaScript is a high-level language, meaning it’s abstracted from the low-level workings of the computer it is running on. Reducing high-level programming calculations to low-level execution takes time. It’s not much time by human standards, but it will start to be noticeable over a few thousand functions and calculations.

History of JavaScript

Netscape employee Brendan Eich created JavaScript in 10 days. Released in September of 1995, the language was part of the beta for the Netscape Navigator web browser. It was first called Mocha, then LiveScript, and three months later the official name changed to JavaScript upon Navigator’s official release.

Explore JavaScript vs. Java programming on Coursera 

Is Java the same as JavaScript? No, but Java and JavaScript are two popular programming languages you can use for a range of personal and professional applications. Whether you're just getting started with programming or want to level up by learning a new language, you can learn at your own pace from leading companies and universities on Coursera.

If JavaScript will be your first programming language, consider enrolling in an introductory online course like JavaScript for Beginners from the University of California, Davis. You'll also practice working with jQuery.

If you have experience with another programming language already, focus on Java fundamentals like data analysis, debugging, and design with an online course like Object Oriented Programming in Java from Duke University.

To sharpen your programming skills at a higher level, consider an intermediate-level Java specialization like Object Oriented Java Programming: Data Structures and Beyond from the University of California, San Diego.