Wednesday Oct 11, 2006

Introduction
JavaScript is a scripting language used in many websites. A scripting language is a language, which is easy and fast to learn. So is this reference. A scripting language is interpreted in run-time. It is not compiled like other languages as C++, C#, VB.NET etc. JavaScript is a client side language and it runs on the client browser. Netscape developed it and because of its simplicity it is one of the most known scripting languages. However JavaScript can be also used on the server-side. JavaScript can be used on all most known browsers. It can be easily used to interact with HTML elements. You can validate text fields, disable buttons, validate forms, or change the background color of your page. All this is possible with JavaScript. Like each programming language, it contains variables, arrays, functions, operators, objects and much more which can be help you to create better scripts for your pages. On the server side you can use JavaScript for example to manage your database entry. JavaScript code can be inserted directly in the HTML or you can place it in a separate file with the .js extension and link the web page with the .js file.

Is JavaScript a lighter version of Java?
Many who haven’t worked before with java or scripting languages think that JavaScript is the same as Java or a lighter version of it. This is not true. Java is a different language developed by Sun Micro Systems. Java is much more complex then JavaScript. In Java you have to declare each variable with the type, in JavaScript you don’t need to do that. All variables are declared when you first time use them. Furthermore in Java you have to declare all variables, functions and classes. In JavaScript you don’t even need to think about these things. Java is compiled to byte codes on the server and the result is send to the client. JavaScript is interpreted on the client side it doesn’t require any compilation.

Usage of JavaScript
Usually web-designers design pages and coders code applications. However with JavaScript a designer has the possibility to create a client side application with very less efforts. He can easily create some kind of dynamic pages – i.e.: you can easily show a prompt box and asks the user to enter his name whenever the page loads for the first time. He can then use the entered value to create a welcome string. These procedures are called events. Events can be used and called when something occurs – like loading the page for the first time. You could also write another event which is called whenever the page is closed. JavaScript is also mostly used to validate text fields. For example in asp.net you have the possibility to validate your controls with some validator controls. These validator controls are basically nothing more then a JavaScript file. This validation can be easily written with JavaScript to verify if a text field is empty or not.