Difference between Java and JavaScript

Key difference: Java is a programming language, which has been influenced by the C language. It derives much of its syntax from C and C++, however it has fewer low-level facilities than either. Java is a general-purpose programming language that is designed to have fewer implementation dependencies as compared to previous languages. Even though their names suggest that Java and JavaScript must be related somehow, it is just not true. JavaScript is an interpreted computer programming language. The main difference between Java and JavaScript is that while Java is a programming language, JavaScript is scripting language. It is a prototype-based scripting language that is dynamic, weakly typed, and has first-class functions.

Java is a programming language, which has been influenced by the C language. It derives much of its syntax from C and C++, however it has fewer low-level facilities than either. Java is a general-purpose programming language that is designed to have fewer implementation dependencies as compared to previous languages. It is concurrent, class-based, and an object-oriented language.

Java was developed by James Gosling at Sun Microsystems and was released in 1995. It was originally released as a core component of Sun Microsystems' Java platform. Sun has since re-licensed most of its Java technologies under the GNU General Public License. This means that all the technology licensed under GNU General Public License is open source and generally available free of cost. Sun Microsystems eventually merged into Oracle Corporation.

Java is designed to allow the same code to run on various platforms. i.e., developers are allowed to “write once, run anywhere” (WORA). Hence, Java applications are typically compiled to bytecode. A class file which contains a Java bytecode can then be run on any Java Virtual Machine (JVM). This would be regardless of computer architecture.

As of 2012, Java has become one of the most popular programming languages for use. This is especially true for client-server web applications. Many other systems have developed alternative implementations of Sun technologies, such as GNU Compiler for Java and GNU Classpath.

Even though their names suggest that Java and JavaScript must be related somehow, it is just not true. JavaScript is an interpreted computer programming language. The main difference between Java and JavaScript is that while Java is a programming language, JavaScript is scripting language. It is a prototype-based scripting language that is dynamic, weakly typed, and has first-class functions. However, like Java, JavaScript is heavily influenced by the C programming language. JavaScript also borrows many names and naming conventions from Java, but it does have very different semantics than Java.

JavaScript takes its key design principles from the Self and Scheme programming languages. It is a multi-paradigm language that supports object-oriented, imperative, and functional programming styles.

JavaScript was formalized in the ECMAScript language standard and was originally implemented as part of web browsers. It allowed client-side scripts to interact with the user, control the browser, communicate asynchronously, and alter the document content that was displayed. However, JavaScript is also used in applications outside of web pages, such as in PDF documents, site-specific browsers, and desktop widgets. Furthermore, newer and faster JavaScript VMs and frameworks have also increased the popularity of JavaScript for server-side web applications.

There are various similarities between Java and JavaScript, such as both have a C-like syntax. They are both object-oriented and typically sandboxed, especially when used inside a browser. Also, JavaScript was designed with Java's syntax and standard library in mind. All Java keywords were reserved in original JavaScript. JavaScript's standard library follows Java's naming conventions, and JavaScript's Math and Date objects are based on classes from Java 1.0.

However, they are much more different than they are similar. Some differences between Java and JavaScript:

  • JavaScript has many functional programming features based on the Scheme language.
  • Java is an OOP programming language while Java Script is an OOP scripting language.
  • JavaScript, does not create applets or stand-alone applications unlike Java.
  • Java has static typing; JavaScript's typing is dynamic. In dynamic typing, a variable can hold an object of any type and cannot be restricted.
  • JavaScript is weakly typed while Java is strongly typed.
  • Java is loaded from compiled bytecode; JavaScript is loaded as human-readable source code.
  • Java's objects are class-based; JavaScript's are prototype-based.
  • JavaScript has many functional programming features based on the Scheme language.
  • Java creates applications that run in a virtual machine or browser while JavaScript code is run on a browser only.
  • Java code needs to be compiled while JavaScript code are all in text.
  • They require different plug-ins.
  • Java can stand on its own while JavaScript must be placed inside an HTML document to function.
  • Java is larger and a more complicated language. While, JavaScript is easier and more robust than Java.
  • Java must be compiled into what is known as a "machine language" before it can be run on the Web.
  • JavaScript is geared to web pages. Java is geared toward where it is needed most at the time.
  • Java constructors are special functions that can only be called at object creation; JavaScript "constructors" are just standard functions.
  • Java requires all non-block statements to end with a semicolon; JavaScript inserts semicolons at the ends of certain lines.
  • Java uses block-based scoping; JavaScript uses function-based scoping.
  • Java has an implicit this scope for non-static methods, and implicit class scope; JavaScript has implicit global scope.
  • JavaScript supports closures; Java can simulate sort-of "closures" using anonymous classes.
  • All JavaScript functions are variadic; Java functions are only variadic if explicitly marked.
  • JavaScript prototypes can be redefined at runtime, and has immediate effect for all referring objects. Java classes cannot be redefined in a way that affects any existing object instances.
  • JavaScript allows methods in an object to be redefined independently of its prototype; methods in a Java object are tied to its class, and cannot be redefined at runtime.

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