Thursday, August 7th, 2008

This Week in HTML 5: Mark Pilgrim’s new blog series

Category: HTML

<p>I am really jazzed about the first entry in a new series on HTML 5. Mark Pilgrim (of Python, Greasemonkey, Open Web, writer extraordinaire, and creator of Google Doctype) has started the series This Week in HTML 5 which aims to keep us up to speed on the spec, and progress across the board (what are browsers implementing etc).

In the first episode he discusses the progress with workers, interesting clarification around providing text instead of images, and more.

Anyway, over to Mark:

The biggest news is the birth of the Web Workers draft specification. Quoting the spec, “This specification defines an API that allows Web application authors to spawn background workers running scripts in parallel to their main page. This allows for thread-like operation with message-passing as the coordination mechanism.” This is the standardization of the API that Google Gears pioneered last year. See also: initial Workers thread, announcement of new spec, response to Workers feedback.

Also notable this week: even more additions to the Requirements for providing text to act as an alternative for images. 4 new cases were added:

  1. A link containing nothing but an image
  2. A group of images that form a single larger image
  3. An image not intended for the user (such as a “web bug” tracking image)
  4. Text that has been rendered to a graphic for typographical effect

Additionally, the spec now tries to define what authors should do if they know they have an image but don’t know what it is. Quoting again from the spec:

If the src attribute is set and the alt attribute is set to a string whose first character is a U+007B LEFT CURLY BRACKET character ({) and whose last character is a U+007D RIGHT CURLY BRACKET character (}), the image is a key part of the content, and there is no textual equivalent of the image available. The string consisting of all the characters between the first and the last character of the value of the alt attribute gives the kind of image (e.g. photo, diagram, user-uploaded image). If that value is the empty string (i.e. the attribute is just “{}“), then even the kind of image being shown is not known.

  • If the image is available, the element represents the image specified by the src attribute.
  • If the image is not available or if the user agent is not configured to display the image, then the user agent should display some sort of indicator that the image is not being rendered, and, if possible, provide to the user the information regarding the kind of image that is (as derived from the alt attribute).

Great to see this series kick into gear, and having Mark keep us in the loop on the very important HTML 5 effort.

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