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You may well ask: “How can I start using HTML5 if older browsers don’t support it?” But the question itself is misleading. HTML5 is not one big thing; it is a collection of individual features. So you can’t detect “HTML5 support,” because that doesn’t make any sense. But you can detect support for individual features, like canvas, video, or geolocation.
<video> tag; there is also a corresponding DOM API for video objects in the DOM. You can use this API to detect support for different video formats, play a video, pause, mute audio, track how much of the video has been downloaded, and everything else you need to build a rich user experience around the
<video> tag itself.
Chapter 2 and Appendix A will teach you how to properly detect support for each new HTML5 feature.
Love it or hate it, you can’t deny that HTML 4 is the most successful markup format ever. HTML5 builds on that success. You don’t need to throw away your existing markup. You don’t need to relearn things you already know. If your web application worked yesterday in HTML 4, it will still work today in HTML5. Period.
Now, if you want to improve your web applications, you’ve come to the right place. Here’s a concrete example: HTML5 supports all the form controls from HTML 4, but it also includes new input controls. Some of these are long-overdue additions like sliders and date pickers; others are more subtle. For example, the
Read all the gory details about HTML5 forms in Chapter 9.
“Upgrading” to HTML5 can be as simple as changing your doctype. The doctype should already be on the first line of every HTML page. Previous versions of HTML defined a lot of doctypes, and choosing the right one could be tricky. In HTML5, there is only one doctype:
Upgrading to the HTML5 doctype won’t break your existing markup, because all the tags defined in HTML 4 are still supported in HTML5. But it will allow you to use — and validate — new semantic elements like
<footer>. You’ll learn all about these new elements in Chapter 3.
Whether you want to draw on a canvas, play video, design better forms, or build web applications that work offline, you’ll find that HTML5 is already well-supported. Firefox, Safari, Chrome, Opera, and mobile browsers already support canvas (Chapter 4), video (Chapter 5), geolocation (Chapter 6), local storage (Chapter 7), and more. Google already supports microdata annotations (Chapter 10). Even Microsoft — rarely known for blazing the trail of standards support — supports most HTML5 features in Internet Explorer 9.
Tim Berners-Lee invented the world wide web in the early 1990s. He later founded the W3C to act as a steward of web standards, which the organization has done for more than 15 years. Here is what the W3C had to say about the future of web standards, in July 2009:
Today the Director announces that when the XHTML 2 Working Group charter expires as scheduled at the end of 2009, the charter will not be renewed. By doing so, and by increasing resources in the HTML Working Group, W3C hopes to accelerate the progress of HTML5 and clarify W3C’s position regarding the future of HTML.
HTML5 is here to stay. Let’s dive in.
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Copyright MMIX–MMXI Mark Pilgrim