HTML and CSS Reference
In-Depth Information
This is becoming increasingly important: a SecuritySpace Technology Penetration
Report found that as of January 2010 over 64% of websites included JavaScript (see ) .
The work of ARIA specification is still being done, and while support is fairly robust
and always improving, there are bugs and incomplete support in user agents to contend
The good thing is that implementing ARIA doesn't have to be hard. It's definitely not
harder than building cross-browser, custom JavaScript widgets. And you're already
doing that, right?
7.1 Writing Appropriate alt Text Descriptions
You want to add a text alternative for an image.
Add the text alternative programmatically using the alt attribute of the image.
If an image deserves a text alternative that can be summed up in one to two sentences
(or about 75 words or less), set that text as the value of the alt attribute:
<img src="next_button.jpg" alt="Go to the next page." >
Alternative text should not exceed 150 characters.
How do you know how well the alternative text works? A good rule of thumb is, “If
you replace every image on the page with its text alternative, the page conveys the same
meaning as when the images are displayed.”
If the image is complex, like a chart or diagram, and cannot be simply summarized,
include the additional information adjacent to the image or link the image to a longer,
more detailed text alternative:
<a href ="diagram_desc.html"><img src="diagram.jpg" alt="Diagram that shows how
to assemble the item with a link to the assembly instructions"> </a>
If providing additional information beyond an alt attribute, ensure that
the text is updated whenever changes are made to the associated image.
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