Java vs. JavaScript: What’s the Difference?

They Sound Similar but Java and JavaScript Have Many Differences

Just because Java and JavaScript look somewhat alike, many people think they are the same thing or different versions of the same thing. In reality, however, there is a big difference between Java and JavaScript. Both are programming languages, but they have very specific purposes and work in different ways. 

Java vs JavaScript
Java
  • Works best for desktop programs and stand-alone applications.

  • It is a pure OOP (object-oriented programming) language.

  • It is used primarily for server-side applications.

  • Must have a Java Virtual Machine (JVM) to run.

  • Uses more memory. 

JavaScript
  • Lightweight OOP web-based scripting language.

  • Provides form validation and interactivity (animations) on websites.

  • Used for client-side programming.

  • Supported by most web browsers.

  • Uses very little memory to run.

The major difference between Java and JavaScript is what they do. Using Java, you can create stand-alone applications (called applets) which are mini programs that run on a desktop computer or the web and even mobile platforms like Android. JavaScript is a text-based language that the developer inserts into HTML and CSS code to use on a website. 

You have to compile Java, which means after coding, the developer puts it through a process that compresses it and turns it into a single program. Then it must be used on an operating system or server that has Java Virtual Machine (JVM) installed on it. Whereas, JavaScript can easily be typed into an HTML page, uploaded to the web server, and used within seconds. Nothing more than a web browser is required to read and run the code. 

What Does Java Do? 

Pros
  • Write once, run everywhere model.

  • Easy to debug using compiling tools.

  • Supported by most operating systems. 

Cons
  • Requires Java Virtual Machine (JVM) to run.

  • Must be compiled into bytecode before using it.

  • Harder to learn and code.

  • Not human-readable.

Java was developed by James Gosling of Sun Microsystems in 1995 and first released in 1996. Java began as merely a desktop application programming language but quickly turned to a web-based solution. One benefit of using Java is that it creates a nice, neat, packaged solution. The developer codes the application, runs it through a compiler, and the result is an applet that may be used on a computer or called from a browser with a plugin. Java is primarily a server-side application meaning it does not run within the browser but can be viewed “through” it. 

Java is supported by almost all operating systems, but it requires special plugins to run within a browser. The compiling process makes it easier to discover and correct bugs before distribution. However, Java is a complex language with dozens of libraries, frameworks, APIs, plugins, and it requires the Java’s Virtual Machine (JVM) to run. Java code is not human-readable, and some developers are moving away from using it due to concerns over security and compatibility. 

Today, Java is used most often for enterprise solutions, big data, scientific calculations, credit card processing, and Android apps. It is also employed in server-side applications such as Apache, JBoss, Geronimo, and GlassFish. Oracle owns Java, and the mantra they use to describe the Java process is “write once, run everywhere.”

A quick example of Java code is this snippet below, which creates a random number that a programmer could use for various purposes, especially with encryption and security applications.

A small Java applet that creates a random number.

What Is JavaScript? 

Pros
  • Integrates easily with HTML and CSS programming.

  • Uses less memory and is more robust than Flash.

  • Easily readable and any developer can customize snippets of code for their own use.

  • Easy to learn and use quickly. 

Cons
  • Can only run in a web browser. 

  • Must customize the code for different browsers/environments.

  • Harder to debug.

JavaScript is a light, easy-to-learn text language that developers can insert into HTML and CSS pages to add interactivity, animations, and things like form validation to web pages. As Flash has died out, JavaScript has taken over because it is powerful, flexible, and reusable. JavaScript is primarily a client-side application meaning it runs right in the web browser without having to grab any code from a remote server. However, the invention of Node.js has opened up options for server-side applications. JavaScript developers share snippets of code, customizable libraries, classes, and frameworks to allow you to code complex applications quickly. 

The best thing about JavaScript is that it is human-readable, and any programmer can examine the code and figure out what it does. It integrates seamlessly with HTML and CSS but sometimes has to be customized for the environment to run correctly. JavaScript only runs in a web browser; it does not have desktop capabilities. It is also harder to debug because you can only witness issues when testing it live in a web browser.

Programmers love JavaScript for its lightweight flexibility. It is most often used in front-end applications such as jQuery, AngularJS, and Backbone.js. JavaScript can also be used on the server-side using Node.js, which is a JavaScript runtime environment allowing it to work outside of a web browser. Some examples of companies using Node.js for their web applications are Netflix, PayPal, Microsoft, Uber, LinkedIn, eBay, and Walmart. 

An excellent example (from w3schools.com) of JavaScript in action is the one below which uses a jQuery snipped and a form field to filter the results in a table. When the user types in any portion of the first name, last name, or email address, the table switches the non-matching rows to “hidden” instantly. The code below illustrates how little work you need to do to perform incredible functions easily. 

Short JavaScript code that filters a table list.

Which Language Is the Best for Your Application?

Deciding to use Java or JavaScript depends on a few factors, and it may come down to personal preference. If your application will run on a mobile platform or is geared towards an enterprise solution, then Java makes the most sense. If you are looking to add dynamic interaction to a website using jQuery for immediate search results, then JavaScript is a better bet. Java and JavaScript share qualities, which means they overlap in some capabilities, but it should be clear, which will work best for your specific project. 

When considering server-side applications, the decision to use Node.js vs. Java is a personal one that you will have to decide for yourself. Learning both Java and JavaScript are a plus for any developer who wants to expand their marketability.