a element can’t have an
alt is for providing alternative text for an image that can’t be loaded/perceived, so it wouldn’t make sense to use it for a hyperlink.
a that can be relevant for accessibility
(Leaving technical things like using the correct
dir, or adjusting
tabindex if needed, aside.)
title, the general rules for the
title attribute apply: You can use it for advisory information, but don’t rely on it.
The spec gives an example how it can be used for links:
On a link, this could be the title or a description of the target resource
For example, you could have a link with the anchor "my website" and a
title that gives the website’s title:
… <a href="http://example.com/" title="John’s blog | Example">my website</a> …
It can be useful to get this additional information (e.g., it might save the visitor a click, for example because they already know this site by its title), but it’s not a problem if it’s not there (or if the visitor doesn’t notice that it’s there or if the visitor can’t access it).
hreflang attribute should be used if the target is in a different language than the document you are linking from.
… <a href="http://de.example.com/foo" hreflang="de">German translation</a> …
A user agent could announce/warn, offer to translate, etc.
If the link anchor text is in a different language than the rest of the document, you should use the
lang attribute. If the target is also in this (or another) language, use
hreflang in addition.
… German translation: <a href="http://example.com/de/hallo-welt" lang="de" hreflang="de">Hallo Welt</a> …
A user agent (e.g., a screen reader) could use the corresponding language module for reading it.
type attribute should be used if the target is not a HTML document, e.g., for PDFs, MP3s, etc.
… <a href="http://example.com/foo.ogg" type="audio/ogg">Download OGG</a> …
A user agent could warn, or open it in a different context, etc.
rel attribute is used to specify link types. Most link types don’t play a special role for accessibility, but there might be some (depending on your link purpose).
For example, it’s conceivable that the
external link type (example) could be relevant (a user agent might decide to open these links in a different context), or the
help link type (a user might offer a quick way to open these links), etc.
… <a href="http://example.com/help" rel="help">Help</a> …
accesskey attribute can be used to associate a keyboard shortcut for visiting the link. But this should only be done in very specific cases (e.g., for a page’s primary link of a link aggregator site).