Java vs. JavaScript 

An introduction to the difference between Java and JavaScript from purpose for creation to contemporary use and function.

At first glance a lot of newcomers to coding may assume that the programming languages of Java and JavaScript are synonymous if not related and functioning with a measure of interconnectivity. It’s a common and presumable misconceptions as two of the most iconic coding languages and having both come into vogue in the 1990s, not to mention the latter being named for the former. While both have many facets in common, it’s the difference between Java and JavaScript that defines them (despite their similarly caffeinated names – and yes, coffee was the inspiration). It’s notably rare that separate applications can be interchangeably used. So, what’s the difference between Java and JavaScript, what are they, how are they used, and is one better than the other? 

What is Java? 

Oak, DNA, Silk, and Green were possible names for James Gosling’s newly minted, object-oriented programming language back in the early 1990s, but the one he settled on was Java, named after the Indonesian coffee. Gosling, a Canadian computer scientist employed by Sun Microsystems (now owned by Oracle) created Java in 1991 alongside Mike Sheridan and Patrick Noughton and released it for public use four years later.  

Over 20 years later, Java is now pervasive: Android apps, Hadoop, web server applications, enterprise desktop applications, retail, banking — Java is everywhere. Thus, it shouldn’t be surprising that it’s consistently ranked as the most preferred (and often lucrative) programming language.  

Designed with a syntax inspired by C/C++, the core promise of Java that programmers would find familiar and approachable, was Write Once, Run Anywhere (WORA) which would ensure no-cost runtimes on the most in-demand platforms. When being used for web development, Java has long been the go-to programming language for applications on Google’s Android platform. 

 Java hosts a wide array of advantages: 

• Gold standard for Android, enterprise and desktop applications. Java was the original cornerstone of Android app development. With Java comes a huge community of developers, alongside any and all tools and frameworks an application would need.
• Speed and performance. One of the advantages of being a compiled language is that it means Java runs extremely fast.
• Mobility across platforms. The Java Virtual Machine (JVM) makes it easy to run Java applications on any OS or device with JVM installed.
• Easy to learn. There are few programming languages that feature as short a learning curve as Java. It’s been around forever and that means if a problem exists, it’s already been encountered and solved, and you’ll likely find countless tutorials and guides that should make troubleshooting a breeze.

Of course, there are some things that may not lead you to believe that Java is right for you. Java does require a high degree of available memory, and its popularity and longevity also means that hackers have had a good crack at exploiting its vulnerabilities. Thankfully, this also means that security professionals have spent just as much time with it and security best practices are well understood. 

What is JavaScript? 

JavaScript is a scripting language designed to run in a web browser, allowing web pages to become interactive and dynamic. Despite the obvious similarity in their name, JavaScript was actually not designed by the same team or company that brought us Java — though the name choice was, of course, inspired by the then newly-released Java.  

JavaScript was developed in 1995 by Brendan Eich of Netscape, a company best known for their once industry-leading web browser Netscape Navigator, back in a time before first Internet Explorer and then Google Chrome dominated the market. The nascent World Wide Web was just starting to explode, thanks in large part to Netscape Navigator’s graphical interface which allowed even the most non-technical users to access the Internet for the first time.  

Back then, however, web pages were only able to depict static images and text, without any ability for dynamic behavior once the page had loaded. This necessitated a new scripting language, specifically designed for web browsers, a “glue language” for designers and programmers. And if it could utilize a similar syntax to the increasingly popular Java, all the better. That language became JavaScript. Alongside HTML and CSS, it is now considered one of the big three core components of the web, being utilized on over 97% of all websites.   

As the scripting language of choice for making websites interactive, JavaScript advantages include: 

• Core technology of the web. JavaScript is such a huge, ubiquitous part of the Internet, that you’ll find it simple to utilize for almost any web-based project, with a host of libraries and tools at your disposal for web development as well as an active community of developers.  
• Can work outside of web now with Node.js. Thanks to the introduction of Node.js in 2009, what was once a strictly web-only scripting language can now be access on the front and back end.  
• Easy to learn. This is one Java and JavaScript have in common, especially since they both rely on a simple syntax. For many, JavaScript will be one of the very first programming languages they learn.   

Though its simplicity and single-threaded nature can cause it to fail in certain specific contexts where newer, more complicated languages would not, ultimate JavaScript is still the best at what it was designed for. 

Java vs. JavaScript: Major similarities 

There’s a running joke in programming—Java is to JavaScript as ham is to hamster. Ultimately, the similarity in the names (though no coincidence, as JavaScript’s developers were specifically invoking Java) suggests a correlation that does not truly exist. That said, despite their many differences, there are nonetheless some broad strokes similarities worth considering, especially if you are looking at web development when comparing Java to JavaScript, where both platforms can be implemented.  

• Object-Oriented Programming (OOP). This is likely the biggest similarity and is the one justification for the likeness in the names. When using Java and JavaScript, developers will need to write their code in terms of objects and their corresponding relationship to each other. This can give both languages access to techniques like inheritance and encapsulation. 
• Many concepts are utilized in both languages. JavaScript’s language was inspired by Java’s own which results in obvious similarities between the two. Concepts utilized in both include: common procedural structures (if, for, when, etc.), exception-based error handling with stack unwinding, declarative syntax to modify methods and classes, and a lexical scope.  
• Can be used for both front-end and back-end development. This point historically has not always been true. JavaScript was developed specifically for coding within web browsers, working with what users will actually see and interact with on the page, and so has traditionally always lived on the front-end for client-side development. Java is a general purpose language by its very design, so it can live in both worlds, but has traditionally been favored for back-end server-side development. With the advent of Nodes.js, however, JavaScript can actually now be used for development on the server-side.  
• Easy to get started. Perhaps the most important similarity, especially for someone trying to decide which of these coding languages to begin learning, isn’t even a technical one. As Java and JavaScript are both iconic coding languages used by countless developers over the past decades, there is a wealth of information out there to help you begin your journey. Many newer languages are more difficult to penetrate, and you can find the guidance and tutorials you would need to really dig in either harder to find or less comprehensive. But the coding world has made it quite simple to get started with Java or JavaScript.  

Major differences in Java vs. JavaScript: 

Remember: The difference between Java and JavaScript, in addition to a variety of uses and functions, can be traced back to the source in that were developed to serve entirely different purposes. They were never intended to be used interchangeably, and they’re not simply competing versions of the same tool that are intended to be used the same way and it doesn’t come down to simply choosing the superior product. 

To recap, while Java was designed for general purpose, approachable programming, that would grant developers an easy ability to build their own standalone applications. Its development began before consumers had widescale access to the Internet, and the focus was on programming consumer electronics, like VCRs and interactive TVs.  

JavaScript, on the other hand, was development exclusively with the World Wide Web in mind and was envisioned as a scripting language that could run on the browser.  

Let’s take a closer look at some of the major differences between these two languages. 

• Compiled vs. Interpreted. Java is a compiled programming language while JavaScript is considered an interpreted scripting language. What’s the difference? It’s all in the implementation. While Java is compiled into bytecode and runs on a Java Virtual Machine (JVM), JavaScript’s syntax can be interpreted directly by a web browser.  
• Static vs. Dynamic Type Checking. JavaScript, like most scripting languages, uses dynamic typing which allows type safety to be verified at runtime. Java, on the other hand, uses the less-common static typing where the type of variable is checked at compile time. What’s the difference? There’s a lot to it, but in short, static data typed languages require the programmer to explicitly define a data type when they create a piece of data. This is not required of dynamic type checking which can give you more flexibility and enable you to write code faster, though can also more easily lead to errors. 
• Concurrency.  When it comes to handling the execution of several instruction sequences at the same time (or concurrently), this is handled very differently between the two platforms. Java utilizes multiple threads in order to perform tasks in parallel while JavaScript was initially designed as single-threaded. As it more modernly exists as Node.js for server-side applications, JavaScript now handles concurrency on one main thread of execution via a queue system called the event loop, and a forking system called Node Clustering. Generally speaking, both methods are fine and work just as well, but at the end of the day, Java is going to be generally faster because thread to thread memory sharing is certainly much faster than interprocess communication (IPC). 
• Speed. It is difficult and perhaps flawed at a fundamental level to try to ascertain which of Java and JavaScript is faster. So much depends on the context in which they’re being used. When run on a virtual machine, as Java generally is, Java is much faster because it’s a compiled language, with built-in support for multithreading and concurrency. On the other hand, JavaScript’s nature as an interpreted language allows for a quick start-up process that Java does not. Ultimately, you’re gaining and losing speed at different portions of the process and it likely comes down to a wash.  
• Security. Java and JavaScript have been around for a long time, giving hackers and security experts alike plenty of opportunities to understand where each language’s vulnerabilities lie. In the case of Java, your biggest security issues are going to come from SQL injections and XML external entities (XEE) while those using JavaScript need to instead be more concerned about cross-site scripting (XSS) attacks and JavaScript or Node.js code injections into web forms and other page features.  

Which is better? 

When two things are being compared, any two things, one of the first things people want to know is… which is better? As you might imagine, asking which is better between Java and JavaScript is a little like asking which is a better screwdriver, Phillips or flat head? Neither is better, of course, they’re two different tools which are useful for different things.  

So, if you’re trying to decide between which of the two to use, it depends a lot upon what you want to use them for. Consider what it is that you are trying to build and what resources you have at your disposal. Java is a general purpose programming language, designed to work easily most anywhere, that can build most anything. Even despite recent updates, JavaScript is most at-home on a web-based platform.  

For some general guidance consider the following: 

Projects that Java is ideally suited for: 

• Applications for Android 
• Server-side applications like Apache, Glassfish, WildFly, etc.
• Enterprise Software
• Big data analytics and scientific computing
• General purpose programming of hardware

Meanwhile, JavaScript presents a host of other opportunities. It represents the best option when and if your project involves the following: 

• Adding interactive behavior to web pages, including web forms, slidable carousels of images, audio and video, animations, drop-down menus and more.
• Web and mobile apps developed through Node (some notable examples include the mobile apps for Netflix, Uber, and PayPal).
• You’ll be able to access JavaScript code libraries that can provide developers with existing code for routine programming features to build web and mobile applications around.
• Web servers and server applications.

This list is introductory more than comprehensive. Programming has grown very complex if not complicated in the years since Java and JavaScript were developed, and there may well be a specific nuance to your programming plans not included in this overview on the basic comparative differences.  These best practices are only meant as a point from which you can begin, providing a feel for what can be expected when assessing which of these two iconic coding languages will best suit individual or case-by-case programming needs.