JavaScript is a cross-platform, object-oriented scripting language invented in web browsers to make web pages more dynamic and give feedback to your user. Adding JavaScript to your HTML code allows you to change completely the document appearance, from changing text, to changing colors, or changing the options available in a drop-down list, or switching one image with another when you roll your mouse over it and much more.
JavaScript is mainly used as a client side scripting language. This means that all the action occurs on the client’s side of things. When a user requests an HTML page with JavaScript in it, the script is sent to the browser and it’s up to the browser to do something with it. In fact, JavaScript is often used to perform operations that would otherwise encumber the server, like form input validation. This distribution of work to the relatively quick client-side service speeds up the process.
JavaScript is supported by many popular Web browsers, including all remotely recent versions of Microsoft Internet Explorer and Netscape Navigator, but sometimes you have to turn on the capabilities in your browser preferences.
One of the main advantages of JavaScript is an ability to get information about the browser and HTML page. This access to information gives JavaScript great power to modify the browsing experience.
Most importantly, JavaScript isn’t overly tough to use. Its syntax is quite similar to C, C++ and Java. However, it is much easier to learn and implement.