What is the difference between Java and JavaScript?

Understanding the key differences between Java and JavaScript

If you’ve ever wondered what the difference between Java and JavaScript is, you’re not alone. While these two terms may sound very similar, they are distinctly different applications used within the IT industry, each with varying purposes. That’s not to say both Java and JavaScript don’t overlap, of course, with each application also sharing some important similarities between themselves.

In order to discover how Java and JavaScript are both different and similar, it’s important to first learn what each application is, as well as its purpose, features, advantages, and disadvantages. Having this thorough understanding of Java and JavaScript will also offer key insight into which application you should use for your next project, helping you to get the job done quickly, efficiently, and successfully.

We’ve covered all of this and more in our insightful guide about Java vs JavaScript. Keep reading to learn all there is to know about these hugely popular and groundbreaking applications. 

Difference Between Java and JavaScript

  1. Java
  2. JavaScript
  3. 3. Java vs JavaScript
  4. 4. What is similar between Java and JavaScript?
  5. 5. Java vs JavaScript: which should you use?

1. Java

Java is a general-purpose programming language and computing platform for application development. It is commonly used for tasks such as:

  • Back-end development projects, including those involving big data and Android development
  • Desktop computing
  • Other mobile computing
  • Game development
  • Numerical computing

Today, our internet is heavily saturated with Java-based programming, and we have Java to thank for the many applications that make our day-to-day life easier, such as search engines, social media apps, medical devices, cloud-based storage, and so much more.

Java was developed by James Gosling at Sun Microsystems in 1991 and released into the world in 1995. Surprisingly, Java’s creation was accidental, as Gosling and his team were building a set-top box and began “cleaning up” the C++ program language currently being used. The result was an entirely new programming language they named Oak at the time. This was soon renamed Java when they discovered Oak was a name already registered for a computer company.

In 2009, Sun Microsystems was acquired by Oracle Corporation. To date, Java is one of the most widely used programming languages in the world. In fact, it is used by 95% of enterprises as their primary programming language. Additionally, the Java language is central to the Android operating system, which powers the largest share of the world’s smartphones.

Some of the well-known companies which use Java include:

  • Google
  • Instagram
  • Netflix
  • Pinterest
  • Airbnb
  • Uber
  • Spotify

To create an application using Java, you first need to download the Java Development Kit (JDK), which is available for Windows, macOS, and Linux. Then, you write the program using the Java programming language, before a compiler turns the program into what’s known as Java bytecode. Java bytecode can be described as the instruction set for the Java Virtual Machine (JVM), which is a part of the Java runtime environment (JRE). This Java bytecode runs without modification on any system that supports Java Virtual Machines and allows your Java code to be run anywhere.

Features of Java

Java offers several features, including:

  • It uses a compiler to execute codes
  • The ability to write code once and run it on almost any computing platform
  • It is designed for building object-oriented applications
  • It is a multithreaded language with automatic memory management
  • It enables distributed computing as it is network-centric

Key benefits of using Java

Java offers several key benefits to users, which contribute to its status as one of the most popular programming languages in the world. Let’s take a look at each of these below.

  • Platform-independent. Java is a platform-independent programming language, meaning you can write your code once and then run it anywhere, on any platform that has a JVM (Java Virtual Machine) installed in it. Java can therefore be used to create programs that can run across desktops, mobiles, and embedded systems, helping users to create a wide array of applications to meet their needs.
  • Multi-threading. Java also supports what is known as multi-threading, which means it contains two or more parts that can run concurrently, and each part can handle a different task at the same time. Therefore, Java has the capability to perform numerous tasks simultaneously, making it a highly efficient platform for users.
  • Robust and secure. Java is celebrated for offering a highly secured environment for application development. Not only is it able to handle and remove errors, but Java also has the ability to reduce the risk of crashing, prevent the attacks of viruses, and monitor for the misuse of resources. This robust security gives users immense confidence when using the platform.
  • Dynamic and extensible. Another key benefit of Java is the fact that it is a dynamic and extensible language since it is designed to adapt to an evolving environment. All the classes, objects, methods, and libraries in Java are dynamically linked in Java. As an extensible language, Java also supports various functions that are written in other languages. This includes the widely used C and C++, which are commonly used for graphics-heavy software such as games, photo and video editing apps, and browsers.
  • Ease of use. Java was designed primarily with ease of use in mind, and it is, therefore, simpler to write, compile, debug, and learn than most other programming languages. There are also open-source implementations of Java, including Sun’s Java implementation (the most popular version), meaning it is free to use in production.
  • A wide range of resources is available. Because Java is one of the most popular programming languages and computing platforms for application development, there is a large and very active community offering support, forums, resources, and other opportunities. Java User Groups (JUGs) are volunteer organizations that share Java-related knowledge around the world, while the Oracle Technology Network (OTN) provides links to Java APIs, blogs, downloads, and more.

Disadvantages of Java

While Java offers several benefits, the programming language and computing platform do have some drawbacks. These disadvantages include:

  • Slow speed. When compared to other programming languages such as C and C++, Java is known to perform significantly slower. This is due to the Just-In-Time (JIT) compiler, which compiles bytecodes to native machine code at run time as well as the extra level of compilation and abstraction by the Java Virtual Machine. Additionally, the garbage collector function consumes more CPU time. This is because all other threads have to be paused to allow the garbage collector thread to work.
  • High memory and processing requirements. Despite Java’s efficiency, the program does require high memory usage and processing requirements to execute tasks. Because of this, hardware costs increase, so it isn’t always a budget-friendly option for developers.
  • Lack of support for low-level programming. While Java is excellent at providing developers with the resources they need to perform high-level programming constructs, it sadly does not provide the same amount of support for executing low-level programming constructs. One such construct is pointers, which is an object in many programming languages that stores a memory address. Instead, developers must do pointer manipulation in C++ or C.
  • Little control over garbage collection. Java’s garbage collector (GC) is a background process that provides automatic memory management for the Java environment. It does so by controlling the deallocation of a program’s computer memory resources. Unfortunately, the garbage collection feature doesn’t provide users with functions such as “Delete” or “Free,” resulting in a lack of user control.

2. JavaScript

Now that you’ve learned what Java is, let’s turn our attention to JavaScript. JavaScript is an object-oriented, text-based scripting language that allows users to create interactive elements on web pages. Along with HTML and CSS, it is one of the three core languages used to develop websites.

Although JavaScript is mostly used for web-based applications and web browsers, it can also be used in software, servers, and embedded hardware controls. It is the most popular language among developers and without it, we would not have useful and widely-used web apps such as Google Maps and eBay.

Just some of the other, well-known companies which use JavaScript include:

  • Facebook
  • PayPal
  • Groupon
  • Microsoft
  • Slack

JavaScript’s origins can be traced back to 1995 when a Netscape programmer named Brandan Eich developed it within just 10 days. In the 1990s, companies such as Netscape and Microsoft played a key role in the early days of the internet. Netscape’s Navigator and Microsoft’s Internet Explorer were up against each other in a browser popularity war, with each competing to come out on top. Hence, Netscape knew it had to develop a game-changer for the world wide web if it was going to have a chance at success.

The new scripting language was originally named Mocha, but quickly became known as LiveScript. Developers then settled on its final name, JavaScript, shortly after. The name came from Netscape’s support of Java applets within its browser. However, many believe it was also a marketing tactic to divert some attention from Java, which was the most buzzed-about language during this time.

Although JavaScript’s popularity got off to a slow start, it is now used to build 97.5% of websites today, including some of the world’s most successful, such as Facebook and YouTube. These days, JavaScript is commonly used for a wide variety of projects, including:

  • Adding interactive behaviour to web pages
  • Creating web and mobile apps
  • Building web servers and developing server applications
  • Game development

Features of JavaScript

  • It’s a cross-platform language
  • It can be used for both client-side and server-side
  • It has a strong testing workflow
  • It’s simple and quick to learn and to start coding with
  • It has added dependencies

Key benefits of using JavaScript

Just like Java, JavaScript offers a wide range of benefits to those who use it. We delve into each of these in more detail below.

  • Client-side scripting language. Unlike other programming languages, JavaScript is known as a client-side language. JavaScript code on a website gets processed on its own using the resources that are available on the system of the user. Therefore, there is no need for any server-side browser to process the code. This means the source code is processed by the client’s web browser, rather than on the web server, and 97.5% of websites use it for this exact purpose.
  • Powerful frameworks. JavaScript provides a number of powerful and robust frameworks that can help in the development process. These frameworks are pre-built groups of codes that are put together to make development easy and hassle-free for users. These collections of code are also easily adaptable, allowing developers to quickly and easily customize it for their needs.
  • Procedural programming features. Procedural programming uses a structured approach to coding, where the functionality of the program is broken down into a number of functions to make it easier to follow. This also greatly reduces the need to repeat code and therefore allows users to make their web apps more creative.
  • Concurrency. Users can conduct multiple tasks at the same time in JavaScript by using a single thread. Executing several tasks simultaneously saves both time and effort on the user’s behalf, thus contributing to JavaScript’s popularity among coders and developers.
  • Easy to get started. JavaScript’s syntax was inspired by Java’s and is relatively easy to learn compared to other popular languages like C++. The structure is simple for both users and developers to understand. Additionally, because JavaScript is everywhere on the web, there are countless resources available to help anyone learn how to use it efficiently.
  • Extended functionality. There are numerous add-ons available, that help the developers build JavaScript applications a lot faster and easier than with other programming languages. One popular third-party add-on is Greasemonkey (a Mozilla Firefox extension), which allows developers to add bits of predefined code into their code to save time and money.

Disadvantages of JavaScript

Like all programming languages, JavaScript isn’t without its shortcomings. We’ve listed JavaScript’s key disadvantages below.

  • Client-side security. If the browser can run your JavaScript code, then any person can view your source code through the browser’s View Source feature. The problem here is that someone may then use the code for malicious purposes, including using the source code without permission or verification. This can also make it easier for someone with ill intent to place a snippet of code into the website that compromises the security of data over that site. Because of this, some people choose to disable JavaScript entirely.
  • Lack of browser support. Different browsers will interpret JavaScript differently, requiring developers to test the code across various platforms before it is published. Furthermore, older browsers won’t always support some of the newer JavaScript functions, resulting in additional testing. Thankfully, these days the differences are minimal, so if you test your code first, you shouldn’t have any issues.
  • Lack of debugging facility. Unfortunately, client-side JavaScript currently lacks a debugging facility. This means finding errors in your script can be extremely difficult, as the browser itself doesn’t display the contents of registers or variables if a program terminates unexpectedly. The most common errors experienced are load-time errors, runtime errors, and logic errors. It is only through becoming familiar with what causes these errors generally that a user may learn the ways to solve them.
  • Single inheritance. JavaScript doesn’t support multiple inheritances, which is when an object can inherit the properties and values from unrelated parent objects. Instead, it utilizes what is known as single inheritance. Instead, property value inheritance happens at run time by JavaScript searching the prototype chain of an object to find a value. Because an object only has a single associated prototype, JavaScript cannot dynamically inherit from more than one prototype chain.
  • Rendering errors. A single code error can stop the rendering of the entire JavaScript code on a website, making it appear to the user as if JavaScript was never present in the first place. JavaScript for Google, for example, doesn’t work the same way as HTML and must be executed. When something disrupts this rendering, it can cause a failure in how the site is supposed to appear and the content that should be displayed. JavaScript render problems can therefore seriously impede user experience, not to mention the ability of search engines to index your website as well.

3. Java vs JavaScript

In 2009, web developer Jeremy Keith coined the now-famous phrase: “Java is to JavaScript as ham is to the hamster.”

So bottom line, how are Java and JavaScript different?

Java is a general-purpose, object-oriented programming language and computing platform for application development, while JavaScript is an object-oriented scripting language that allows users to create interactive elements on web pages.

Let’s examine the key differences between Java and JavaScript below.


Java is primarily used for all server-side development. Its purpose is to enable developers to:

  • Write software on one platform, but be able to run it on virtually any other platform
  • Create programs that can run within a web browser and access available web services
  • Develop server-side applications to power online forums, e-commerce stores, polls, HTML forms processing, and so much more
  • Combine applications or services using the Java language to create highly customized or unique applications or services
  • Write robust and efficient applications for mobile phones, remote processors, microcontrollers, wireless modules, sensors, gateways, consumer products, and basically any other electronic device you can think of

JavaScript, however, is predominantly used for writing client-side scripts for tasks such as JS validation and interactivity. It is used to create responsive and interactive elements for web pages, which help to enhance the user experience, as well as for creating web and mobile apps. Just some of the common interactive elements made using JavaScript include:

  • In-browser games
  • Video players
  • Animations
  • Interactive maps
  • Menus

Applications run differently

Applications created using either Java or JavaScript run very differently from each other. Java develops applications that can run in a browser or what’s known as a Java Virtual Machine (JVM), whereas applications made using JavaScript can run on a browser only. With JavaScript, there is no need for any initial setup, however, Java requires the installation of JRE and JDK for applications and programs to run in the Java Virtual Machine.


Java can be used to create complete applications that can run on a single computer or be supplied among servers and clients in an entire network. It can also be utilized to build simply designed, small applications for use as part of a web page. Referred to as “applets”, these mini-applications make it possible for a web page user to interact with individual components of the page.

The usability of Java applications is diverse, as they can be found everywhere from Android, desktop, banking, and financial applications, to data search engines, cloud-based systems, artificial intelligence software, and more.

The use of JavaScript, on the other hand, is limited to making web apps more interactive and creative. Where HTML and CSS are languages that give structure and style to web pages, JavaScript gives web pages interactive elements that engage the user. Therefore, you may find JavaScript being used in the following ways:

  • Displaying date and time
  • To authenticate the user input before submission of the form
  • To open or close new windows or tabs
  • To display dialogue boxes and pop-ups
  • To change the look of HTML documents
  • To create forms that respond to user input without having to access the server

Compiled vs Interpreted

Although Java and JavaScript are both considered to be languages, they are vastly different types of languages that also differ in the way they run. Java is a compiling language, meaning Java code is compiled into bytecode and run on Java Virtual Machine.

JavaScript is an interpreted scripting language, which means it’s read and understood directly by a browser in the composition in which the code has been written.


Despite both Java and JavaScript being object-oriented, they also differ in this approach. Objects of Java are class-based, therefore you cannot make any program in Java without first creating a class. Alternatively, JavaScript is an object-based language based on prototypes, rather than being class-based. Because of this different basis, it can be less evident how JavaScript allows you to create hierarchies of objects and to have the inheritance of properties and their values.

File Extension

Java programs have the file extension “.Java” and translate source code into bytecodes, which is executed by a Java Virtual Machine. JavaScript files have the file extension “.js” and are interpreted but not compiled. Every browser has a JavaScript interpreter to automatically execute JS code.


Both Java and JavaScript have different approaches to concurrency, which is the ability to run several programs or several parts of a program at the same time. Java has a thread-based approach to concurrency, known as multithreading.

Multithreading means that you have multiple threads of performance inside the same application. A thread is like a separate central processing unit (CPU) accomplishing your application. Thus, a multithreaded application is like an application that has multiple CPUs executing different parts of the code simultaneously.

JavaScript, however, has an event-based approach to concurrency and runs on a single thread. Because this thread is event-based, it only executes the code, collects and processes events, and executes queued sub-tasks when they occur.

Type checking

Java is static and known as a strongly typed language. This means the programming language enforces strict restrictions on intermixing of values with different data types and when a restriction occurs, it results in an error.

JavaScript, on the other hand, is dynamic and considered a weakly typed or “untyped” language. In other words, you don’t have to specify what type of information will be stored in a variable in advance. This flexibility lets you move more rapidly, change things faster, and repeat at a quicker speed.


Both Java and JavaScript also differ greatly in their approaches to security. As we learned earlier in this guide, Java is favoured by many developers due to its high level of security. Java prides itself on keeping the “security of codes” as the primary motive that can be achieved through a Java Virtual Machine. This results in the source code being hidden, as it’s compiled into the unreadable byte coding type.

JavaScript, however, lacks this same level of security and allows the source code to be ready by any person as it is written in plain text. Because JavaScript is less secure, users must make efforts to secure its coding from things such as cross-site scripting.

4. What is similar between Java and JavaScript?

Now that you’ve learned about the main differences between Java and JavaScript, let’s take a look at the ways in which they’re similar to each other. 

Object-oriented programming (OOP)

Both Java and JavaScript are forms of object-oriented programming (OOP), meaning they organize software design around data, or objects, rather than functions and logic. More specifically, both programming languages provide code for creating objects and their interactions or relationships with each other.

As a result, both Java and JavaScript are based on shared principles including:

  • Encapsulation
  • Abstraction
  • Inheritance
  • Polymorphism

Front-end development

We mentioned this earlier in the guide, but both Java and JavaScript are the most popular web app development languages. In fact, both programming languages are used by more than 90% of enterprises. Their similarities also lie in their front-end development. JavaScript is employed as a framework or library for front-end development after being embedded directly into HTML. Additionally, Java can be used as a Java applet for creating attractive front-ends.

Back-end development

Java and JavaScript can also be used for back-end development. Java has been used to support back-end technologies such as JBoss, WebSphere, and Apache for several years now. Additionally, when it comes to powering JavaScript servers, Node.js offers the essential environment for back-end development.


Java and JavaScript also have browser capability, allowing each of them to be capable of running in a browser. JavaScript is the preferred choice for web developers, as it can run on most modern browsers without any issues. Although less popular, Java-driven Java Applets can also run in web browsers, however, compatibility and security remain a concern for developers when using this method.

Libraries and frameworks

Both Java and JavaScript have a wide range of library and framework options available to assist developers and programmers. These resources provide access to general and purpose-specific code that can be reused over and over again for different projects, thus saving time and effort on the developer’s end.

5. Java vs JavaScript: which should you use?

In the previous chapters, you learned about Java and JavaScript, including the ways in which they’re both similar and different. By now, you may be wondering which one is best to use for your project: Java vs. JavaScript?

When it comes to programming languages, your choice should come down to what you’re trying to build and what resources you have at your disposal. While JavaScript is very much a web technology, Java is more of a general-purpose language that can build anything.

When it comes to web applications, both Java and JavaScript work well. However, as Java is multithreaded and the code is compiled at once, the execution of Java applications is faster than what JavaScript can achieve.

In saying this, however, Java needs to be carried on the server-side, which actually slows down the user interaction. Therefore, for small and interactive web applications, JavaScript is recommended. This is because the code is lighter and executed on the client-side, which allows it to facilitate quick feedback and interactivity.

Another reason why you may wish to use JavaScript for your next project is that its web development time is quicker than Java. However, this only applies to smaller projects. For large and complex desktop and mobile software — such as developing Android applications, enterprise software, and server-side technologies — Java is the better option. This is particularly due to its availability of APIs and third-party libraries, which gives it the advantage.

Therefore, you should consider Java if your project involves:

  • Android apps
  • Enterprise software
  • Scientific computing
  • Big data analytics
  • General-purpose programming of hardware
  • Server-side technologies such as Apache, NGINX, JBoss, Geronimo, or GlassFish

Alternatively, you should consider JavaScript if your project involves:

  • Dynamic single-page applications (SPAs)
  • Front-End technologies, including jQuery, AngularJS, Backbone.js, Ember.js, ReactJS etc.
  • Server-Side technologies, such as Node.js, MongoDB, Express.js, etc.
  • Mobile App Development through PhoneGap, React Native, etc.

Java vs JavaScript: The bottom line

After reading this in-depth guide, you’ve now learned that while Java and JavaScript sound similar, they are ultimately very different applications used within the IT industry for varying purposes. While they each have some elements in common — such as the fact that they’re object-oriented and offer browser compatibility, as well as front- and back-end development — ultimately, their differences are far greater.

Of course, no platform can be deemed greater than the other, as their success ultimately comes down to what it is you want to achieve. For small and interactive web applications, JavaScript is recommended, as its web development time is quicker than Java for this purpose. However, for large and complex desktop and mobile software — such as developing Android applications, enterprise software, and server-side technologies — Java is considered the better option.

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