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This Week in HTML 5 – Episode 32

Wednesday, May 6th, 2009

Welcome back to "This Week in HTML 5," where I'll try to summarize the major activity in the ongoing standards process in the WHATWG and W3C HTML Working Group.

In this article:

Introducing the <hgroup> element

Topping our list of changes this week is the new <hgroup> element:

The hgroup element represents the heading of a section. The element is used to group a set of h1–h6 elements when the heading has multiple levels, such as subheadings, alternative titles, or taglines.

Meanwhile, the <header> element has been redefined:

The header element represents a group of introductory or navigational aids. A header element typically contains the section's heading (an h1–h6 element or an hgroup element), but can also contain other content, such as a table of contents, a search form, or any relevant logos.

Here is an example of how these elements can work together in marking up a specification:

  <h1>Scalable Vector Graphics (SVG) 1.2</h1>
  <h2>W3C Working Draft 27 October 2004</h2>
  <dt>This version:</dt>
  <dd><a href=""></a></dd>

Relevant background reading:

(Re)introducing the accesskey attribute

Next up in this week's changes is the reintroduction and reformulation of the accesskey attribute. In HTML 4, the accesskey attribute allows the web designer to define keyboard shortcuts for frequently-used links or form fields. In HTML 5,

All elements may have the accesskey content attribute set. The accesskey attribute's value is used by the user agent as a guide for creating a keyboard shortcut that activates or focuses the element.

If the accesskey attribute is used on a non-link, non-form-field element, it defines a command, which has a specific meaning in HTML 5.

Also new in HTML 5: the accesskey attribute may contain a number of shortcuts, space-separated, and the new .accessKeyLabel DOM property contains the shortcut key that the browser ultimately chose.

One possible enhancement, not in HTML 5 but under consideration for HTML 6, is the use of more-than-1-character strings to define roles, such as accesskey="help". The browser could then choose the appropriate shortcut key based on the user's platform and preferences.

I plan to write up a more detailed history of the accesskey attribute in a seperate article. Until then, here is some background reading:

(Re)introducing the window.setTimeout and window.setInterval functions

The window.setTimeout and window.setInterval functions have been in a state of limbo in the HTML 5 spec, waiting for an editor to take them and split them out into a separate spec. No editor has come forward, so back into HTML 5 they go.

These timer functions are complicated by their unique history in browser-land. They can take basically anything as their first argument. If you pass a function, it will be executed after the specified interval. If you pass anything else, the browser will call toString() on the parameter and then evaluate it as a JavaScript expression in the context of the current window (or, if the timer function is called from a web worker, the current WorkerUtils object). There is also a little-known but widely supported third argument to setTimeout and setInterval, which passes arguments to the evaluated expression. Meanwhile, the second argument -- the timeout value -- can also be any datatype. Browsers must call toNumber(toString(timeout)) and round down to the nearest integer.

More <video> changes

It seems that each week in HTML 5 brings more changes to the <video> element. While this is not strictly true, it is certainly true this week.


Speaking of events, there was a series of event-related checkins this week. The onundo and onredo events, usually triggered by the user selecting the Undo or Redo item from the Edit menu, have been moved from the Document to the Window. [3003] These events are important for all sorts of web applications (think Google Docs and then work your imagination outward).

r3004 adds support for the onbeforeprint and onafterprint events, which are supported in Microsoft Internet Explorer since version 5.

r3005 updates the global list of event handlers to include these new events, some video-related events, some storage-related events, and several others that have slipped through the cracks during the thrashing of these features.

Other interesting changes this week

Around the web

Tune in next week for another exciting episode of "This Week in HTML 5."

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