JavaScript is a scripting language. It is a trademark of Sun Microsystems. The main use of JavaScript is to interact with HTML that provides HTML a programming tool. Its looks like JAVA but it is more easy and flexible than JAVA. JavaScript uses prototypes instead of classes for defining object properties. It also supports most of the current browsers. It is a client side language. You can validate text fields, disable buttons, validate forms, or change the background color and many more with your page.

 JavaScript also has the variables, arrays, functions, operators and objects like other programming languages. 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. JavaScript is added to HTML commands by using the SCRIPT tag. Java and JavaScript are two completely different languages in both concept as well as design.

JavaScript can read and change the content of an HTML element. The word document.write is a standard JavaScript command for writing output to a page. JavaScript script library is very beneficial and in use these days. Some examples of JavaScript libraries are: JQuery, Prototype, script.aculo.us, and JavaScript widget libraries.

JQuery Jquery is a JavaScript library that emphasis interaction between JavaScript and library. It is a single file that contains DOM, Event, Effects, and Ajax functions. It is basically a JavaScript framework for writing huge task of JavaScript with few lines of code. Prototype Prototype is a JavaScript Framework that focuses on to ease development of dynamic web applications.

It is easy-to-use toolkit for class-driven development and the nicest Ajax library around. Mootools also works in the same manner; it is Object-Oriented JavaScript framework designed for the intermediate to advanced JavaScript developer. These days what could be done previously with JavaScript only can often be done with CSS. For e.g. CSS menus, tabs, sub-menus, or rollovers that all needed JavaScript, can be done with CSS.