Accessibility

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Websites built with accessibility in mind are flexible in meeting different user needs, preferences and situations. Though these methods can increase usability for everyone who uses the Web they are often legally required to be implemented in a specific effort to prevent discrimination against people with disabilities.

Contents

Starting points

These are some readable introductions to accessibility that cover; what accessibility is, why it is important, as well as practical advice.

Moodle-related accessibility coding guidelines

Use CSS, but still use headings, strong and emphasis
It is generally a good idea to separate a document's content HTML from how it is presented using CSS. There are some tags that affect a document's presentation but also contribute to the structure and meaning of the content. These tags should remain in HTML. This includes heading tags <h1>, <h2>, <h3>..., which are used to form the document's hierarchical structure, and <strong> and <em> tags, which are used to add meaning to sections of text.
Avoid using background images for important information
Users of non-visual browsers cannot see images. They can read the alt tags of normal images, but background images are not presented like normal images.
Image alt and title attributes
  • An alt attribute is required (even if empty) on all images.
  • If a link is wrapping an <img>, the <img> does not need a title attribute if the link has one.
  • The alt for an image and the title for its surrounding link should usually differ. An image alt attribute provides a text equivalent to an image, whereas a title attribute adds supplementary information about the purpose or action associated with an image link. Simply repeating the same text in alt and title attributes adds little and can be annoying for screen reader users.
Links and buttons should be selectable and easily click-able
  • An image used as an icon for a user to click should be large enough so that the user can click on it easily.
  • Users should be able to navigate to all links and buttons using the keyboard.
  • Generally we should avoid having two buttons/links that achieve the same action in the same area. This can be annoying and confusing for users of screen readers.
Support dynamic interaction with ARIA attributes
Events triggered by AJAX and JavaScript can be less obvious to users of non-visual browsers. ARIA attributes can assist users of such browsers to follow a dynamic change.
Use labels with inputs
Context can easily be lost without a visual presentation. Labels are needed on all input input elements (except button) to describe their purpose in a form. Labels should be unique on a page. Repeated elements should have a unique label that identifies the element within its context.
Use appropriate page titles
A page title is a starting point for a screen reader. Page titles should be unique and should make sense for the page. Avoid generic page titles.
All pages should be navigable using just a keyboard
It should be possible navigate to all points on a page just using a keyboard. Important events triggered by a mouse event should be able to be triggered when the item receives focus through keyboard navigation.
Avoid using colour alone to express meaning
Colour-blind users need additional information to gain meaning if colour is used as the emphasising feature. Also keep in mind that colours can have differing significance in different cultures, so colours should be configurable either through settings or language files.
Role for button-type links
If a link acts as a button (not forwarding to another page, which is often the case when combined with Javascript), it should declare the role attribute button. Also, as a button is usually triggered by the Space bar, the Javascript should add proper event listeners on the link to accept this key. Read more at Mozilla Developer Network

Web standards, guidelines and legislation

International

USA

UK

See also the Equality Act 2010 Statutory Code of Practice (PDF) for Services, public functions and associations.

Germany

European Union

Tools

Firefox extensions

Accessibility validation tools

Screen readers

See also this long list of accessibility tools.

See a live demonstration of a number of accessibility tools.

Resources

Dive Into Accessibility by Mark Pilgrim
Building Accessible Websites by Joe Clark (online version)

See also

Personal tools
In other languages
User docs (English)