Difference Between Java and Javascript

Many of the answers here seem to mostly just cover the superficial differences between JAVA and JavaScript.

The short answer, as you might have noticed, is that they are very different languages, despite the similarity in name.

Unlike VBScript being a script version of Visual Basic, JavaScript is not a script version of JAVA.

You’ve seen that many have noted that JAVA is a compiled language and JavaScript is a scripting language.

What this generally implies is that JAVA is not going to be changing how it’s code works at runtime (although, that’s not precisely impossible), and JavaScript is likely to.

Because JAVA is compiled ahead of time, it is often much easier for IDEs (and other developers) to see exactly how your code was intended to operate before it’s in use.

Difference Between Java and Javascript

Difference Between Java and Javascript
Difference Between Java and Javascript

This can improve the experience, but many IDEs are getting smarter about JavaScript, and JavaScript is improving a bit, too.

Also, certain types of performance enhancements can be made as a result of compiled languages that are not typically inherent in scripted languages.

JavaScript was originally built in just a few short weeks, so you can imagine that it’s far from a perfect language.

That being said, Brendan Eich was a genius in implementing a few core concepts. First, he made functions as variables.

At the time this was extremely rare in programming languages. Second, he made JavaScript extremely extensible.

Third, as a scripting language for the web, it was very open (everyone could see it), really helping the open-source community thrive on the web.

JavaScript is an extremely flexible language. This is both its blessing and its curse.

To give an example.

When I’m writing JAVA code, I’m frequently required to write lots of boilerplate code just to get something running.

I’m constantly telling JAVA things I feel it should already know since I already told it those things about 5 other times in 5 other places.

There are lots of restrictions on how I’m able to do things. But — and this is pretty big when you’re working with other developers — it’s usually much more clear what I’m doing. There’s much more safety built into the language.

JavaScript can be a bit more loosey-goosey. I can easily write code that does the same thing in about 10 different ways.

Indeed, I can easily write code that writes code that does what I want.

This really helps with things like keeping code DRY (Don’t Repeat Yourself), but all sorts of confusion can result if you don’t practice discipline — which many coders don’t do in rushed environments, which is how many environments are.

People have mentioned the whole prototype thing. With very few exceptions, I have learned to try to stay away from inheritance in JavaScript.

The composition is much better and more intuitive in most cases.

The biggest issue I’ve had in JavaScript has been all the different libraries and frameworks.

Because of the loose requirements in JavaScript, these libraries can be difficult to work into some of the projects you own.

Difference Between Java and Javascript

Sometimes they add their own flavor of how to do things which seems as different as trying to combine.

Net and Spring frameworks (these are from two different languages) together, with the exception that it seems possible to do in JavaScript until you realize what a mess you’ve gotten yourself into and you can’t figure out how to escape.

So, in short,

JavaScript is extremely flexible and easy to learn and use, but not easy to learn to do well, particularly since it requires lots of self-discipline.

JavaScript is pretty much the only language available for browser development, but precompilers are making it easier to write in other languages that are transformed into JavaScript.

JAVA has lots of built-in rules enforcement, making it more difficult to screw things up as badly as you can with JavaScript, but often requiring way more boilerplate code which will force certain design decisions.

For instance, even POJOs take more effort to write than an object literals in JavaScript, so Maps will be more likely used in some situations but those often require more work to get the data out of.

I’ve been working with JavaScript since nearly the beginning, and my experience with JAVA is much more limited, so I can’t say what my preference is without including my obvious bias.

That being said, I’ve seen the dark side of JavaScript and it usually comes with developers who lack self-discipline in writing code.

There is no other language I can think of that is so important to use test-first development for.

Many of the issues that come up in JavaScript can be completely mitigated by always writing tests first.

Additionally, it’s easier to write tests first in JavaScript than in many other languages.

This is one area where an ounce of prevention is worth 10+ lbs of cure, so just do it.

Difference Between Java and Javascript

Java is an object-oriented language designed and has always been a full-stack language used in a variety of applications such as Desktop, Web, Enterprise, Embedded, Mobile and Batch applications. Java has inspired quite a lot of languages such as Groovy, Scala, Clojure, Kotlin and has its influence on JRuby and Jython. Android has its syntax similar to Java.

Javascript is an object-based scripting language and has some syntactical similarities with Java. Javascript started its life as a client-side scripting language to do client-side validations, client-side UI elements hiding, display and updates. It then grew to support Ajax asynchronous features giving rise to frameworks and tools such as Jquery, Prototype, and Dojo. It currently has become a full-stack language supporting both client-side and server-side development with Node.js, Express.js, Angular.js, Vue.js and a lot of other JS packages.

Difference between Java and Javascript

  1. Java is an object-oriented language whereas Javascript is an object-based script-based programming language
  2. Java is a statically typed language whereas Javascript is a dynamically typed and loosely coupled language
  3. The Java program is executed by the Java Runtime Environment whereas Javascript is executed by the browser or a javascript engine
  4. Java inheritance is achieved by parent class extended by child class where Javascript inheritance is achieved by reuse of prototype objects
  5. Java code is compiled to bytecode and then bytecode is interpreted during execution. Javascript code is interpreted.
  6. All Java classes are subclasses of ‘Object’ class. Java objects or instances are created from Java class. All Javascript objects inherit from Object.prototype
  7. Popular Java Servers:

Tomcat, JBoss, Weblogic, Websphere

Popular Javascript engine:

Node.js, V8

8. Popular Java Frameworks:

Spring frameworks, JSF, Hibernate, Vaadin, Grails, Struts, Struts 2

Popular Javascript Frameworks:

Express.js, Angular.js, ReactJS, Vue.js, Ember.js, Meteor.js

9. Java IDEs:

Eclipse, NetBeans, IntelliJ Idea, BlueJ, Oracle JDeveloper, JBuilder, MyEclipse, RAD

Javascript IDEs:

WebStorm, NetBeans, Eclipse IDE for Javascript, VS Code, Komodo, Visual Studio 2013, Atom, Sublime Text, Vim, IntelliJ Idea, NeoVim, SpaceMacs, Brackets, Emacs

10. Java mocking tools:

Mockito

Javascript mocking tools:

Sinon.js

difference between java and javascript in tabular form

Programmers, developers and internet users have always been confused between Java and JavaScript.

Many people still think that JavaScript is part of the Java platform, which is not true.

In truth, JavaScript has nothing to do with Java, the only common thing between them is the word “Java”, much like in Car and Carpet, or Grape and Grapefruit.

JavaScript is a client-side scripting language for HTML, developed by Netscape, Inc, while Java is a programming language, developed by Sun Microsystems.

James Gosling is Inventor of Java, popularly known as the father of Java.

While in today’s world calling JavaScript just a client-side scripting language would not be good, as it is now been used in servers also using node.js and people are doing object-oriented development in JavaScript, but that was what it was originally developed.

There are several differences between Java and JavaScript, from how they are written, compiled and executed.

Even the capability of Java and JavaScript vary significantly.

Java is a full feature Object-oriented programming language, used in almost everywhere, starting from programming credit card to server-side coding.

Android uses Java as a programming language for creating Android apps, Swing is a Java API used to create desktop applications and Java EE is a Java platform for developing web and enterprise applications.

On the other hand, JavaScript is primarily used to bring interactivity into web pages, though there are other alternatives like Flash, JavaScript is the most popular one and regaining lots of ground lost earlier with the introduction of powerful and easy to use libraries like jQuery and jQuery UI.

You can use JavaScript to validate user input, create animation and cool effects on an HTML page and can do a lot of interactive stuff e.g. reacting on button click, mouse movement, image click, etc.

In this article, I will share some key differences between Java and JavaScript, mostly from a programmer’s perspective.

Difference between Java vs JavaScript

Here is my list of key differences between JavaScript and Java as programming languages.

I have worked both on them, mainly used Java for all Server Side development, Android and JavaScript for writing client-side scripts to do validation, interactivity, animation and ajax calls.

1) Execution Environment

The first difference between Java and JavaScript is that Java is compiled + interpreted language, Java code is first compiled into class files containing byte code and then executed by JVM, on the other hand, JavaScript code is directly executed by the browser.

One more difference that comes to form this fact is that Java is run inside JVM and needs JDK or JRE for running, on there other hand JavaScript runs inside the browser and almost every modern browser supports JavaScript.

2) Static vs Dynamic Typed language

Another key difference between JavaScript and Java is that JavaScript is a dynamically typed language, while Java is a statically typed language.

This means, variables are declared with type at compile-time, and can only accept values permitted for that type, other hand variables are declared using var keyword in JavaScript, and can accept different kinds of value e.g. String, numeric and boolean, etc.

When one variable or value is compared to other using == operator, JavaScript performs type coercion.

Though it also provides === operator to perform a strict equality check, which checks for type as well.

3) Support of Closures

JavaScript supports closures, in the form of anonymous function. In simple words, you can pass a function as an argument to another function.

Java doesn’t treat the method as the first-class citizen and the only way to simulate closure is by using anonymous class.

By the way, Java 8 has brought real closure support in Java in the form of lambda expression and this has made things much easier.

It’s very easy to write expressive code without much clutter in Java 8.

4) OOP

Java is an Object Oriented Programming language, and though JavaScript also supports class and object, it’s more like an object-oriented scripting language.

It’s much easier to structure the code of large enterprise applications in Java than JavaScript.

Java provides packages to group related class together, provides much better deployment control using the JAR, WAR, and EAR as well.

5) Right Once Run Anywhere

Java uses a byte code to achieve platform independence, JavaScript directly runs on the browser, but code written in JavaScript is subject to browser compatibility issue i.e. certain code which works in Mozilla Firefox, may not work in Internet Explorer 7 or 8.

This is because of browse based implementation of JavaScript. This was really bad until jQuery comes. It’s a JavaScript library that helps to free web developers from this browser compatibility issues.

This is why I prefer to write code using jQuery rather than using plain old JavaScript code, even if its as simple as calling getElementById() or getElementByName() methods to retrieve DOM elements.

7) Block vs Function-based Scoping

Java mainly uses block-based scoping i.e. a variable goes out of scope as soon as control comes out of the block unless it’s not an instance or class variable.

On the other hand, JavaScript mainly uses function-based scoping, a variable is accessible in the function they are declared.

If you have a global variable and local variable with the same name, local will take precedence in JavaScript.

8) Constructors

Java has the concept of constructors, which has some special properties e.g. constructor chaining and ensuring that superclass constructor runs before subclass, on the other hand, JavaScript constructors are just another function.

There are no special rules for constructors in JavaScript e.g. they cannot have return type or their name must be the same as class.

9) NullPointerException

JavaScript is much more forgiving than Java, you don’t have NullPointerException in JavaScript, your variable can accept different kinds of data because of JavaScript is dynamically typed language.

10) Applicability

Last but not least, JavaScript has it’s own space, sitting cozy along with HTML and CSS in Web development, while Java is everywhere.

Though both have a good number of open source libraries to kick start development, jQuery has certainly brought JavaScript to the forefront.

Conclusion

The two languages are completely unrelated.  JavaScript was originally called LiveScript and was renamed when Java was introduced as a kind of cross-marketing. 

There was some hope that they’d be used together and evolve together. 

They never really were; Java applets never took off. 

The two languages have some surface similarities.  They’re both procedural object-oriented languages, so they look more like each other (and like C++ and C#) than they look like, say, Prolog, Lisp, or Haskell.

But within that range, they could hardly be more different. Java is strongly typed, while JavaScript is weakly typed. 

JavaScript has first-class functions; Java lacks them.  Java is class-based; JavaScript is prototype-based.  Java is distributed as compiled bytecode; JavaScript is distributed in its source code.

Experience in one prepares you for the other no more than any other common programming language, like C or Pascal.

If you and your team have good discipline in writing JavaScript, you’ll find that it can be much quicker and easier to write and maintain than many other languages.

If you or they don’t have good discipline, you’ll find that maintaining JavaScript can become a nightmare.

Final Words

That’s all about the difference between Java and JavaScript language.

As I said, they are totally different languages, one is a general-purpose programming language, while the other is a scripting language for HTML.

Though you can do a lot of fancy kinds of stuff using JavaScript, you still don’t have features like multithreading, as compared to Java.

By the way, JavaScript was originally named as Livescrpit, may be due to the fact that it makes your HTML pages live, and the programming world would certainly be free of this confusion, had Netscape hadn’t renamed LiveScript as JavaScript.

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