JavaScript: The Definitive Guide, 7th Edition

Chapter 15. JavaScript in Web Browsers

The JavaScript language was created in 1994 with the express purpose of enabling dynamic behavior in the documents displayed by web browsers. The language has evolved significantly since then, and at the same time, the scope and capabilities of the web platform have grown explosively. Today, JavaScript programmers can think of the web as a full-featured platform for application development. Web browsers specialize in the display of formatted text and images, but, like native operating systems, browsers also provide other services, including graphics, video, audio, networking, storage, and threading. JavaScript is the language that enables web applications to use the services provided by the web platform, and this chapter demonstrates how you can use the most important of these services.

The chapter begins with the web platform’s programming model, explaining how scripts are embedded within HTML pages (§15.1) and how JavaScript code is triggered asynchronously by events (§15.2). The sections that follow this introductory material document the core JavaScript APIs that enable your web applications to:

• Control document content (§15.3) and style (§15.4)

• Determine the on-screen position of document elements (§15.5)

• Create reusable user interface components (§15.6)

• Draw graphics (§15.7 and §15.8)

• Play and generate sounds (§15.9)

• Manage browser navigation and history (§15.10)

• Exchange data over the network (§15.11)

• Store data on ...