Chapter V.3. JavaScript

The problem with most Web pages is that they're static, much like staring at a page from a book except displayed on a computer screen. Although nothing's wrong with static Web pages for displaying information, you may want to create interactive Web pages that can respond to the user's actions. To create interactive or dynamic Web pages, computer scientists developed various programming languages dubbed scripting languages. Although you can choose several languages for creating dynamic Web pages, the most popular scripting language is JavaScript.

JavaScript programs are stored either as part of a Web page file or in a separate file altogether. When you visit a Web site, the computer storing the Web pages (the server) sends its Web pages and JavaScript files to your computer (the client). Your computer now runs an interpreter to run the JavaScript programs.

Instead of creating standalone applications like a systems programming language can do (such as C++ or BASIC), JavaScript programs are often much shorter and designed to create simpler programs. For example, a JavaScript program may display a text box for you to type a password. Whatever you type, the JavaScript program can verify if the password is valid and then decide whether to let you into the Web site.

Because JavaScript works with most browsers and computers, JavaScript is a simple and easy way to create dynamic Web pages without relying on browser plug-ins that users might not have or want. However, ...

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