Introduction to JavaScript

JavaScript is the programming language of the Web. The overwhelming majority of modern websites use JavaScript, and all modern web browsers-on desktop, game consoles, tablets, and smart phones-include JavaScript interpreters, making JavaScript the most ubiquitous programming language in history. JavaScript is part of the triad of technologies that all Web developers must learn: HTML to specify the content of web pages, CSS to specify the presentation of web pages, and JavaScript to specify the behavior of web pages. This book will help you master the language.

If you are already familiar with other programming languages, it may help you to know that JavaScript is a high-level, dynamic, untyped interpreted programming language that is well-suited to object-oriented and functional programming styles. JavaScript derives its syntax from Java, its first-class functions from Scheme, and its prototype-based inheritance from Self. But you do not need to know any of those languages, or be familiar with those terms, to use this book and learn JavaScript.

The name "JavaScript" is actually somewhat misleading. Except for a superificial syntactic resemblance, JavaScript has long since outgrown its scripting-language roots to become a robust and efficient general-prupose language. The latest version of the language(see the sidebar) defines new features for serious large-scale software development.