Java vs. JavaScript Programming Languages: What Are the Differences?

Experienced developers know that the programming languages Java and JavaScript have significant differences. For newer developers, questions about Java and JavaScript’s use are common. 

So, what are the differences between Java and JavaScript? Why do two languages with so many differences have similar names? If you’re an aspiring developer, which one should you learn first? Here, we’ll help you answer all those questions.

Java vs. JavaScript: The similarities and differences

While their names are an obvious similarity, there are many differences between Java and JavaScript. For example, while Java applets can run in a browser, applets are mostly a thing of the past. On the other hand, JavaScript is used to render dynamic content on webpages across the globe. This makes the idea that JavaScript is “the language of the web” while Java is a “backend” language, a true (although incomplete) place to start the comparison. 

To help us make a better comparison, let’s take a closer look at each language.

Java…

• Is an object-oriented programming (OOP) language – Java uses an OOP approach to data and methods. The use of the phrase “programming language” here instead of “scripting language” implies code is first compiled before it can be executed. 
• Is a statically typed language – With static typing, variables are known when code is compiled. This means errors can be caught early in development. 
• Is a compiled language – Generally, Java code is compiled into bytecode before execution. The compiled code is not human-readable. 
• Runs in a Java virtual machine (JVM) – The JVM is where Java code is executed. Because the JVM helps abstract away the underlying operating system, Java code is often very portable.

JavaScript…

• Is an object-oriented scripting language – JavaScript also uses an OOP approach, but it is a scripting language. This means there is no explicit compilation required before JavaScript code can be executed. 
• Is a dynamically typed language – Dynamic typing means variables are checked at execution time. This allows for faster coding but means errors are often caught later in the development process. 
• Is an interpreted language – JavaScript code is stored in plain text and is interpreted in real-time with no compilation required.  
• Runs in a web browser or the Node.js runtime environment – Initially, JavaScript was executed almost exclusively in web browsers. In recent years, JavaScript runtime environments, of which Node.js is the most popular, offer another way to execute JavaScript code outside the browser.

A note on Node.js

The idea that “JavaScript is client-side and Java is server-side” kept things simple in the past. Node.js is changing that. Node.js is a runtime environment that enables JavaScript to run outside of the traditional web browser environment. Thanks to Node.js it is becoming more common for JavaScript code to be used in a wide range of server-side use cases.

Java vs. JavaScript: Why are the names similar?

Why do two very different languages have such similar names? It isn’t to confuse new learners. Let’s go back to the early days of the Java language and JavaScript development to understand why their names are so alike.

What would become the Java programming language and platform was created by The Green Team at Sun Microsystems in 1995. Led by the famous computer scientist James Gosling, the team created a platform-independent, object-oriented, portable, and robust programming language. Initially, the language was going to have the name “OAK”. However, OAK was trademarked by another company, so the team needed to think of an alternative. After considering the names DNA and Silk, the team settled on the coffee-inspired Java. 

Around this same time, Netscape, the company behind the once-popular Netscape Communicator web browser, was working on a way to make web pages more dynamic. Part of this would be achieved using Java and Java Applets, but a simpler solution was needed for more basic tasks. While Java was going to enable enterprise-grade applications, this project had a different target audience: web designers and non-developers. To achieve this goal, Netscape created a scripting language with syntax similar to Java. Initially, the scripting language was named Mocha, then LiveScript. In December 1995, a few months after its release, the name was again changed to JavaScript. Why? According to JavaScript creator Brendan Eich, it was the result of a license agreement between Sun Microsystems and Netscape.

Java vs. JavaScript: Which one should you learn?

Like most questions of this nature in technical roles, it depends. There’s no single right answer to the question of which programming language to learn that will apply to everyone. 

That said, if you’re choosing between Java or JavaScript, here are a few considerations to help you decide:

Learn Java if…

• You want to build desktop applications
• You want to build mobile Android applications
• You want to learn a general-purpose programming language
• You want to work on large enterprise software applications

Learn JavaScript if…

• You want to design the front-end of web apps
• You want to build mobile applications that use PhoneGap/Cordova, jQuery Mobile, Sencha, etc. 
• You want to learn a language with a simple learning curve
• You want to learn a language that is useful on the front-end and back-end of web applications

Ready to start learning one of these programming languages?  If you’re interested in Java, check out this Java Crash Course. If you’d prefer to learn JavaScript, this Complete Javascript Course is for you.