Learning Web Design, 4th Edition

Chapter 20. Using JavaScript

by Mat Marquis

IN THIS CHAPTER

• Meet the DOM

• Polyfills

• JavaScript Libraries

• What Is Ajax?

Now that you have a sense for the language of JavaScript, let’s look at some of the ways we can put it to use in modern web design. First, we’ll explore DOM scripting, which allows us to manipulate the elements, attributes, and text on a page. I’ll introduce you to some ready-made JavaScript and DOM scripting resources, so you don’t have to go it alone. You’ll learn about “polyfills,” which provide older browsers with modern features and normalize functionality. I’ll also introduce you to JavaScript libraries that make developers’ lives easier with collections of polyfills and shortcuts for common tasks.

Meet the DOM

You’ve seen references to the Document Object Model (DOM for short) several times throughout this book, but now is the time to give it the attention it deserves. The DOM gives us a way to access and manipulate the contents of a document. We commonly use it for HTML, but the DOM can be used with any XML language as well. And although we’re focusing on its relationship with JavaScript, it is worth noting that the DOM can be accessed by other languages too, such as PHP, Ruby, Python, C++, Java, Perl, and more. Although DOM Level 1 was released by the W3C in 1998, it was nearly five years later that DOM scripting began to gain steam.

The DOM gives us a way to access and manipulate the contents of a document.

The DOM is a programming interface (an API) for HTML and ...