What is JavaScript and how is it different from Java Technology?

The JavaScript programming language, developed by Netscape, Inc., is not part of the Java platform.

JavaScript, does not create applets or standalone applications. In its most common form today, JavaScript resides inside HTML documents, and can provide levels of interactivity to web pages that are not achievable with simple HTML.

Listed are key differences between the Java and JavaScript.

  • Java is an OOP programming language while Java Script is an OOP scripting 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 vs. JavaScript: Similarities and Differences

They are both similar and quite different depending on how you look at them. First their lineage:

Java is an Object Oriented Programming (OOP) language created by James Gosling of Sun Microsystems. JavaScript is a scripting language that was created by the fine people at Netscape and was originally known as LiveScript. JavaScript is a (very) distant cousin of Java in that it is also an OOP language. Many of their programming structures are similar. However, JavaScript contains a much smaller and simpler set of commands than does Java. It is easier for the average weekend warrior to understand.

You may be wondering what OOP means by now. Object Oriented Programming is a relatively new concept, whereas the sum of the parts of a program make up the whole. Think of it this way: you are building a model car. You build the engine first. It can stand alone. It is an engine and everyone can see it’s an engine. Next you build the body. It can also stand alone. Finally, you build the interior including the seats, steering wheel, and whatnot. Each, by itself is a object. But it is not a fully functioning car until all the pieces are put together. The sum of the objects (parts) make up the whole.

Continuing with the model car example, when you built the engine, you didn’t use any of the parts that would later build the seats (a 350 four-barrel engine with a seat belt sticking out if the piston would look pretty silly). The point is that all the parts that made up the engine were of a certain class of parts. They all went together. Ditto with the body and then the interior.

The point is that in these languages, you build objects out of classes of commands to create the whole. Understand the terminology? Good. Moving along…

Java and JavaScript are Still Two Different Trees

Now let’s talk about how Java and JavaScript differ. The main difference is that Java can stand on its own while JavaScript must (primarily) be placed inside an HTML document to function. Java is a much larger and more complicated language that creates “standalone” applications. A Java “applet” (so-called because it is a little application) is a fully contained program. JavaScript is text that is fed into a browser that can interpret it and then it is enacted by the browser–although today’s web apps are starting to blur the line between traditional desktop applications and those which are created using the traditional web technologies: JavaScript, HTML and CSS.

Another major difference is how the language is presented to the end user (that’s you when you’re surfing). Java must be compiled into what is known as a “machine language” before it can be run on the Web. Basically what happens is after the programmer writes the Java program and checks it for errors, he or she hands the text over to another computer program that changes the text code into a smaller language. That smaller language is formatted so that it is seen by the computer as a set program with definite beginning and ending points. Nothing can be added to it and nothing can be subtracted without destroying the program.

JavaScript is text-based. You write it to an HTML document and it is run through a browser. You can alter it after it runs and run it again and again. Once the Java is compiled, it is set. Sure, you can go back to the original text and alter it, but then you need to compile again.

Java applets run independent of the HTML document that is calling for them (and Java is also what runs many appliances and mobile devices, and does not require a web browser). Sure, they appear on the page, but the HTML document did little more than call for the application and place it. If the programmer allows it, oftentimes parameters can be set by the HTML document. This includes the background color of the applet of the type of text it displays, etc. The delivery of the applet is done through a download. The HTML document calls for the application, it downloads to the user’s cache, and waits to run. JavaScript is wholly reliant on the browser to understand it and make it come to life.

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