Differences between Java and JavaScript

Although both Java and JavaScript has similar names, the two programming languages were invented by different people for different purposes. This article will help you to better understand their key differences and when to use one or the other for your current project.

Java is a programming language originally developed by Sun Microsystems to create stand-alone applications that could run in any operating system that supports Java Virtual Machine or JVM. The JVM is what allows developers to just “write once, run everywhere.”

Java can be used to develop many kinds of applications, including Android applications, desktop applications, and web applications.

JavaScript, on the other hand, is a programming language originally developed by NetScape with the purpose of scripting the web pages, making it interactive to user actions. For example, when you click on a button, JavaScript can manipulate the HTML elements so that the button disappear and a text is shown in its place.

JavaScript was famously created by Brendan Eich in only 10 days and released in December 4, 1995. The scripting language was named after Java because Java is the most popular language at the time. By naming the language JavaScript, developers may associate it with the ease of use and portability of Java.

For a long time, JavaScript was a language that’s primarily used to make the web interactive. It wasn’t until the release of NodeJS in 2009, that JavaScript can be used for back-end and server side development. The release of NodeJS helped JavaScript to compete with long time server-side programming languages such as Java, Python, Ruby, PHP and many others.

JavaScript is now used almost everywhere, from web applications, desktop applications, mobile applications, and even embedded devices.

Key technical differences between Java and JavaScript

The main differences between Java and JavaScript are as follows:

Java is a strongly typed language where you need to declare your variable type during declaration:

public static void main(String[] args) {
  int myNum = 15;
  myNum = "String"; // error incompatible types

JavaScript variable type can be reassigned into any other type at anytime:

let str = "Hello";
str = 7;

Not only variable declarations, but even function declaration in Java also requires you to specify the accessor, whether private or public.

Java is an object-oriented programming language, while JavaScript has a mix of object-oriented and functional programming techniques.

Java needs to be run using Java Virtual Machine, although the machine can be embedded in many devices, including on web browsers. JavaScript runs both on the browser and under NodeJS environment. Like Java Virtual Machine, NodeJS can be run under many devices.

Java code needs to be compiled by Java compiler, while JavaScript will be interpreted as-is by JavaScript runner.


Those are some of the key differences between Java and JavaScript. In short, even though they have the name “Java”, the two programming languages are nothing alike. They are created for different purposes.

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