Java vs. Javascript: Differences and When To Use

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Celso Crivelaro
Celso Crivelaro
Head of Engineering

Table of Contents

Learn more about the key differences between Java and Javascript, and what each of they are used for. Weigh the pros and cons between the two before making the choice for your next tech project.
Published on
April 26, 2023
Updated on
April 11, 2024

Java and JavaScript are two of the most popular programming languages out there. Many confuse the two, considering them the same language or using them interchangeably. Despite their similar names, they are very different languages meant to be used in different situations.

For business owners looking to hire a new developer who aligns with your company’s goals, it’s essential to understand what is Java vs. Javascript and the differences between these two programming languages.

What Is Java Used For?

Since its start 25 years ago, Java has remained at the top of its game as one of the most widely used and popular programming languages, second only to Python. Aside from being a cross-platform, network-oriented, and object-focused programming language, Java is also a computing platform.  

Features of Java

At its core, Java was designed to be portable, easy to use, and secure. One of Java’s best features is that it can be run on almost any computing platform once the code has been written. However, many other traits appeal to Java developers as well, including:


Since Java’s object file format is architecture-neutral, any recorded code can be executed on any processor with a Java runtime system. For example, code written and developed on a computer can also be run on other Java-enabled devices such as cell phones and routers.

Simply put, Java runs on the principle of write-once-run-anywhere (WORA).


Java is also a distributed programming language. In layman’s terms, distributed programming in Java allows programmers to run several nodes in a data center simultaneously on various devices. This benefits users as it increases output and reduces latency in specific applications.

A distributed language such as Java allows several programmers to work on a single project, despite their location. This benefits programmers working to develop larger projects through Remote Method Invocation (RMI).


Java is both dynamic and flexible. Due to its object-oriented behavior, Java programmers can add classes, generate new classes through sub-classes, and add new methods to current classes. In addition, Java allows programmers to use other languages, such as C and C++, to create specific functions.

High Performing

Java can offer high performance to its users due to running on a Just-in-Time compiler (JIT) format and its ability to decrease overhead when being executed. JIT will also enable Java to produce code on demand, ensuring that only the methods used are called on, allowing Java’s applications to run faster.  


Many programming languages are compiled into platform-specific machines. In contrast, Java is compiled into a platform-independent byte code, allowing it to be distributed and interpreted by the Java Virtual Machine (JVM) on any platform operating the code.


Java’s multithreaded function enables programmers to write applications that can execute duties concurrently. In doing so, developers can create interactive operations that operate efficiently.


Java uses public-key encryption for its authentication techniques. Built with security in mind, Java can be used to develop systems free of viruses and outside interference.  


Java is one of the easiest programming languages to learn. Due to its popularity, there are many resources to learn Java. Plus, its code is simple and clean, and it’s known as a general-purpose language, which keeps it user-friendly and a favorite among developers.

Java Pros

  • Popular: Java’s popularity means there is a massive community of developers and many resources to help those new to the programming language. Those looking to start in Java development will be met with a supportive community eager to help. Even intermediate Java developers can benefit from a supportive community and many resources.
  • Easy to use: Ease of use makes Java an easy-to-learn and easy-to-understand programming language that is beginner-friendly. On top of this, Java offers a vast collection of third-party libraries that are easy to navigate.
  • Robust features: Between its multithreaded, object-oriented, and dynamic performances, Java offers developers several unique features to use when developing their applications.

Java Cons

  • Performance: While Java can operate on all operating systems, it requires interpretation during runtime, making the performance run slower than other languages. Additionally, Java runs on JVM, meaning its applications use more memory than other languages.  
  • Cost: Java relies on heavier requirements in processing and memory. As such, Java requires better hardware to operate efficiently. This makes Java a costlier option than other languages.
  • Protection: While Java offers users a lot of security, it lacks its ability to back up and protect data.

What Is JavaScript Used For?

JavaScript, first introduced in 1995, is a text-based or scripting programming language meant to help developers make interactive web pages. However, it can also be used in web applications, game development, and other projects.

Using JavaScript allows developers to execute functional features that could not be done with simple languages such as HTML and CSS.

Features of JavaScript

JavaScript’s primary function is to enable developers to make websites and browser games interactive. JavaScript has several traits that can support its users in creating interactive applications, such as:


JavaScript is not a general-purpose or compiled language. Like Java, JavaScript runs on the JIT compilation, where its code is converted to bytecode before execution.


JavaScript is a platform-independent language that can be written on one device and run anywhere at any time.


JavaScript enables client-side validations. This is an important feature for user experience and allows invalid data to be caught on the client’s side so that the developer can make appropriate fixes immediately.


JavaScript uses prototypes instead of classes; instead of creating classes and objects from them, JavaScript developers can create object prototypes and use those prototypes to create similar objects.


JavaScript is not a compiled language; instead, it is an interpreted one. This means that a browser running JavaScript can interpret its source code, line by line, and execute it.


JavaScript enables developers to handle and create custom events. An example of an event would be a user clicking on a button and then being told to respond to the button with an action. This could look like an information box.


JavaScript is a scripting language that allows client-side execution on browsers. It also contains various libraries for web applications.  


JavaScript contains various control statements, allowing developers to create complicated logic.

JavaScript Pros

  • Speed: Since JavaScript is interpreted, it doesn’t require as much time to execute as compiled languages such as Java. In addition, it can save time in connecting to servers since it is a client-side script.
  • Versatile: JavaScript’s versatility makes it useful for front-end and back-end developers, which means that full-stack developers can benefit from it most. JavaScript can be used with libraries such as NodeJS for those in back-end development and AngularJS or ReactJS for those in front-end development.
  • Functionality: JavaScript supports third-party add-ons, allowing developers to save time and money using predefined code.

JavaScript Cons

  • Debugging: Developers may have difficulty debugging and troubleshooting their code due to browsers not supporting the ability to display errors.
  • Rendering: A single error in JavaScript code can cause the entire website to malfunction and stop rendering.
  • Security: The user can see JavaScript code since JavaScript is a client-side language. This means that others could alter JavaScript code.

Difference Between Java and JavaScript

The primary difference between Java and JavaScript is that Java is a language while JavaScript is a script. As such, JavaScript is operated directly through the browser, while Java is an interpreted and compiled language that can be run across various applications and operating systems.

Other differences between the two include:

  • Variables: Java’s variables need to be declared before being used in programs, whereas JavaScript’s variables can be declared while they are used.
  • Objects: Java’s objects are class-based, while JavaScript’s are prototype-based. Any program developed in Java must be designed alongside a class.
  • Extension: Java’s file extension is .Java. JavaScript’s file extension is .js.
  • Compilation: Java is a compiled language. It is also interpreted. Java’s source code is converted to bytecode and operated through Java Virtual Machine. On the other hand, JavaScript can be executed through any browser with the JavaScript interpreter.
  • Process: Java code is compiled on the server before being executed by the client. JavaScript is interpreted by the client and not compiled.
  • Code: Java is object-oriented and uses classes with inheritance. JavaScript is object-based, using built-in and extensible coded objects without classes or inheritance.
  • Language: Java’s language is static, while JavaScript’s language is dynamic.
  • Syntax: Java’s data types require being declared, whereas JavaScript data types do not.
  • Features: Java features a variety of libraries, is widely used, and has an assortment of tools available for developers to use. JavaScript is versatile and can be used on both front-end and back-end projects, is widely used everywhere, and has many remarkable frameworks available.

Java Developer vs. JavaScript Developer

Which developer you hire will depend on what your company needs in terms of applications. The responsibilities, roles, and salaries between the two vary.

Java Roles, Responsibilities, and Salary

The roles and responsibilities of a Java developer vary depending on the company and position, but they could look like this:

  • Create, execute, and maintain high-volume and low-latency Java applications
  • Ensure high availability and performance
  • Participate in the entire development lifecycle of applications
  • Create testable code that is both well-designed and efficient
  • Carry out testing, debugging, and troubleshooting
  • Manage application development of Java and Java EE applications
  • Adhere to design specifications set forth by the company and senior developers
  • Improve applications and their code continuously
  • Stay up to date on the latest Java applications and features

According to, a Java developer can earn between $83,432 and $111,153, depending on education, skills, and experience.  

JavaScript Roles, Responsibilities, and Salary

JavaScript roles and responsibilities will vary depending on the specific company and job. However, some typical roles and responsibilities include:

  • Create code that is sustainable and can be used in the future
  • Guarantee that the UI/UX designs are practicable
  • Ensure that the front-end website is efficient in performance
  • Improve designs and specifications of applications
  • Perform code analysis, including the requirements, risks, and software reliability
  • Work alongside front-end and back-end developers says a JavaScript developer can earn between $96,705 and $118,767, depending on education, skills, and experience.  

Which One Is Better: Java vs. JavaScript

Neither language is better than the other. Each has its advantages and disadvantages and will suit developers for different tasks.

Use Cases and When To Use

Java is a widely used server-side language for back-end development projects like Android. It can be used for mobile, desktop, numerical computing, and coding games.

Java use cases include:

  • Scientific applications such as MitoMonkey and Orca. Java enables the development of scientific applications due to its assortment of tools and features that allow developers to create environments through simulation.
  • Financial applications such as ATMs that enable bank transactions. Java enables developers to create these apps due to its high performance and scalability.
  • Embedded systems such as Nest Thermostat. This application allows users to remotely monitor and control their energy consumption through Nest devices and apps.

In comparison, JavaScript is commonly used to create browser-based games and interactive webpages.

JavaScript use cases include:

  • Search engines such as Google, Facebook, and others. These use JavaScript to enable results and suggestions when a user is typing.
  • Social media websites such as Facebook, LinkedIn, and Instagram. These use JavaScript in their backend development to help improve their applications.
  • Uber. The ride-share company uses JavaScript to track locations and incoming requests.

Java vs. JavaScript Code Comparison and Examples

Java and JavaScript code may seem similar, but they're very different.

Some examples of Java code include:

Hello, world! program

public class Main {

 public static void main(String[] args) {

  System.out.println("Hello World");



Display current date

import java.time.LocalDate; // import the LocalDate class

public class Main {

 public static void main(String[] args) {

   LocalDate myObj =;  // Create a date object

  System.out.println(myObj);  // Display the current date



Creating a file



public class CreateFile {

 public static void main(String[] args) {  

   try {

     File myObj = new File("filename.txt");

     if (myObj.createNewFile()) {

      System.out.println("File created: " + myObj.getName());

     } else {

      System.out.println("File already exists.");


   } catch (IOException e) {

    System.out.println("An error occurred.");





Some examples of JavaScript code include:

Creating a header

<!DOCTYPE html>




function myFunction() {

document.getElementById("demo").innerHTML = "Paragraph changed.";





<h2>Demo JavaScript in Head</h2>

<p id="demo">A Paragraph.</p>

<button type="button" onclick="myFunction()">Try it</button>



Creating a variable

<!DOCTYPE html>



<h2>JavaScript Variables</h2>

<p id="demo"></p>


// Create and display a variable:

let car = "Fiat";

document.getElementById("demo").innerHTML = car;




Creating a function

<!DOCTYPE html>




function myFunction() {

document.getElementById("demo").innerHTML = "Hello World!";





<p>When you click "Try it", a function will be called.</p>

<p>The function will display a message.</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>



Hire a Javascript or Java Expert

If you are not looking to do the software development of a project yourself, and just looking into which route you should take, Javascript or Java, then adding another team member may be your best bet.  

Instead of spending hours of typing up a job description, going through tons of resumes, and scheduling out interviews, start with Revelo.  We have thousands of highly-vetted javascript developers, that are ready to work as soon as possible.  We help you through the interview, on-boarding, all the way through the entire employment process with our developers, making it easier for you to get back to running your business.

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