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Difference between Java vs JavaScript
| Categories | Java | JavaScript |
|---|---|---|
| Execution Environment | Java code is first compiled into class files containing byte code and then executes by JVM. Java is run within JVM and needs JDK or JRE. |
JavaScript code is directly executed by browser. JavaScript runs within browser and almost each and every modern browser support JavaScript. |
| Static vs Dynamic Typed language | Java is a statically typed language. | JavaScript is a dynamic typed language. |
| Support of Closures | Java doesn't care for method as first class citizen and only way to replicate end is by using anonymous class. |
JavaScript supports closures, in form of anonymous function. In simple words, you can pass a function as an argument to another function. |
| OOP | Java is an Object Oriented Programming language.It provides packages to group related class mutually, then provides much better deployment control by using JAR, WAR and EAR. |
JavaScript also supports class and object; it's more like an object oriented scripting language. It's much easier to structure code of large enterprise application in Java then JavaScript. |
| Write Once Run Anywhere (WORA) | The java used byte code for achieving the platform independence concept. |
It directly runs on the browser, but code written in JavaScript is subject to browser compatibility issue i.e. certain code that work in Mozilla Firefox, may not work in Internet Explorer 7 or 8. |
| Block vs Function based Scoping | Java mostly uses block based scoping i.e. a variable gone out of scope immediately control comes out of the block, unless until it’s not a instance or class variable. |
It mostly uses function based scoping; a variable is accessible in the function when they are declared. If you have a global variable as well as local variable with similar name, then the local variable will take precedence in JavaScript. |
| Constructors | The Java constructors contain some of the special properties (e.g. constructor chaining and ensuring that super class constructor runs previous to sub class. |
The JavaScript constructors are just one more function. Here, there is no special rules for constructors in JavaScript e.g. they cannot have return type or their name must be same as class. |
| NullPointerException | Java have NullPointerException, because Java is a statically typed language. |
JavaScript is much more forgiving than Java, you don't have NullPointerException in JavaScript, and your variable can accept different kinds of data because of JavaScript are dynamically typed language. |
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Learn Java - Java tutorial - java vs javascript - Java examples - Java programs