JavaScript: The Definitive Guide, 6th Edition

Client-Side JavaScript

Client-side JavaScript does not exhibit the nonlinear cross-reference problem nearly to the extent that the core language does, and it is possible to learn how to use JavaScript in web browsers in a fairly linear sequence. But you’re probably reading this book to learn client-side JavaScript, and Part II is a long way off, so this section is a quick sketch of basic client-side programming techniques, followed by an in-depth example.

Chapter 13, JavaScript in Web Browsers, is the first chapter of Part II and it explains in detail how to put JavaScript to work in web browsers. The most important thing you’ll learn in that chapter is that JavaScript code can be embedded within HTML files using the <script> tag:

<html>
<head>
<script src="library.js"></script> <!-- include a library of JavaScript code -->
</head>
<body>
<p>This is a paragraph of HTML</p>
<script>
// And this is some client-side JavaScript code
// literally embedded within the HTML file
</script>
<p>Here is more HTML.</p>
</body>
</html>

Chapter 14, The Window Object, explains techniques for scripting the web browser and covers some important global functions of client-side JavaScript. For example:

<script>
function moveon() {
    // Display a modal dialog to ask the user a question
    var answer = confirm("Ready to move on?");
    // If they clicked the "OK" button, make the browser load a new page
    if (answer) window.location = "http://google.com";
}
// Run the function defined above 1 minute (60,000 milliseconds) ...