The Key Differences Between Java and JavaScript

It’s easy to see why many people may assume that Java and JavaScript are somehow part of the same programming language - or at least very closely related. However, aside from having ‘Java’ in the name and sharing some high-level features, Java and JavaScript are actually quite different. In fact, more experienced developers often point to Jeremy Keith’s observation from 2009 that “Java is to JavaScript as ham is to hamster”.

Here we’ll look at some of the key distinctions between the two, and how they are used in real-life applications. But first, an introduction...

An introduction to Java & JavaScript

Java was developed by James Gosling and a team from Sun Microsystems in the early-1990s. It was designed as a standalone language that is executed in a Java Virtual Machine (JVM), which allows Java programs to run on any platform or device. The first version was released in 1995, and Time Magazine listed Java as one of the ten best products of the year. Java is one of the most popular programming languages around today, and it is widely used in web development, mobile devices, games, e-commerce, artificial intelligence (AI) and many other applications. You can read more about the importance of Java here.

JavaScript had a different name when it was developed in the mid-1990s by Netscape employee Brendan Eich, who wanted a new programming language that could make websites more visually dynamic. First known as Mocha and LiveScript, the name JavaScript was reportedly chosen to capitalize on the popularity of Java at the time (thus creating the Java/JavaScript confusion). JavaScript, of course, has become the de facto language of the internet, used in more than 97% of all websites and powering most basic dynamic features of web pages today. You can read a bit more here about why we think JavaScript may still be the language of the future.

Key differences between Java & JavaScript

Aside from the similarities in the name, Java and JavaScript are both examples of the broad object-oriented programming (OOP) paradigm, which means the code defines ‘objects’ that interact with each other and perform actions. These days, both can be used in front-end and back-end development, though as we’ll see below, one may be better suited than the other for certain tasks or projects. Another similarity is that both Java and JavaScript have the strong support of large communities and a wealth of tutorials, libraries and frameworks to help developers.

Beyond these high-level properties, let’s examine some of the main differences between Java & JavaScript:

• Programming vs Scripting: Java is an OOP programming language, while JavaScript is an OOP scripting language. The main difference here is that programming languages traditionally need a compiler to be deployed, whereas scripting languages do not require this step as they can already be interpreted. With Java, the source code is compiled to bytecode and run as a machine-level language in the JVM. JavaScript is written in plain text and interpreted directly by the internet browser.
• JVM vs Browser: One of the key features of Java is that it is executed in a JVM, which means it can run on any platform or device that has JVM installed on it. JavaScript is written and executed alongside HTML in the web browser and is also widely compatible.
• Strongly-typed vs Weakly-typed: Java is considered a strongly-typed language, which means that each type of data is predefined by the programming language and all variables must be defined before being executed. This enforces consistency in the code, though some think it may limit creativity. JavaScript is a weakly-typed language where variables can be declared as they are used. Though describing something as ‘weak’ may have negative connotations, in this case, it means JavaScript is a dynamic language.
• Class-based vs Prototype-based Objects: A class-based OOP language like Java has a clear distinction between a ‘class’ and an ‘instance’ - you define an abstract class and then instantiate it. A prototype-based OOP language like JavaScript does not use this distinction and inheritance is implemented via a process of cloning existing objects.

• Multi-threading: Java supports multi-threading, which means it can run multiple tasks or programs at the same time. This can lead to a more efficient use of computing resources. JavaScript is single threaded, so only one line of code can be executed at any given time.

Java is mainly used for…

• Developing mobile and web applications. Java is a top choice for development on Android.
• Enterprise software and solutions. Java owner Oracle estimates that there are 25 billion active cloud JVMs.
• Server-side technologies like Apache, used for developing web applications.
• General purpose programming of hardware devices.

JavaScript is mainly used for...

• Adding interactive behavior and dynamic features to web pages.
• Dynamic Single-Page Applications (SPAs).
• Front-end technologies like jQuery and AngularJS, though since the development of Nose.js JavaScript is also increasingly used with server-side technologies too.
• Browser-based game development.
• Web and mobile applications.

The final verdict

It’s not about picking a ‘winner’ here. The choice between Java and JavaScript will depend on what needs to be done and what language a particular developer is more familiar or comfortable with. Both are hugely popular, have a strong community and abundance of resources to help anyone learn, and continue to broaden their uses. Here at Jobsity, we have developers that are skilled with using both Java and JavaScript, so get in touch to find out how they can help with your next development project.

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