Javascript

JavaScript was developed by Netscape Communications Corporation, the makers of the popular Netscape Web browser. JavaScript was the first Web scripting language to be introduced, and it is still by far the most popular.

Note

JavaScript was originally called LiveScript and was first introduced in Netscape Navigator 2.0 in 1995. It was soon renamed JavaScript to indicate a marketing relationship with Java.

JavaScript is almost as easy to learn as HTML, and it can be included directly in HTML documents. Here are a few of the things you can do with JavaScript:

• Add scrolling or changing messages to the browser's status line.
• Validate the contents of a form and make calculations. (For example, an order form can automatically display a running total as you enter item quantities.)
• Display messages to the user, either as part of a Web page or in alert boxes.
• Animate images or create images that change when you move the mouse over them.
• Create ad banners that interact with the user, rather than simply displaying a graphic.
• Detect the browser in use and display different content for different browsers.
• Detect installed plug-ins and notify the user if a plug-in is required.

You can do all this and more with JavaScript, including creating entire applications. We'll explore the uses of JavaScript throughout this book.