Keyboard accessibility is one of the most important aspects of web accessibility as it affects many individuals with disabilities. Think about how one uses a mouse, to move a cursor around a screen to click on items of interest. Users who are blind don't use a mouse because the cursor is by design a visual way to interact with your computer. Users with certain mobility disabilities don't have the ability to grasp or click a mouse since it often requires fine motor skills. if your web site is not keyboard accessible, it is excluding many individuals from using it.
2.1.1 Keyboard: All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. (Level A)
2.1.2 No Keyboard Trap: If keyboard focus can be moved to a component of the page using a keyboard interface, then focus can be moved away from that component using only a keyboard interface, and, if it requires more than unmodified arrow or tab keys or other standard exit methods, the user is advised of the method for moving focus away. (Level A)
One of the easiest ways to determine if you web site has at least minimal access, and for those testing for accessibility is to use only your keyboard to navigate to all items on your page. Unplug or set aside your mouse and try to navigate.
Most PC browsers allow you to navigate a web site using the TAB key to move forward through the links, and SHIFT-TAB to move backwards. In some cases, you might have to navigate menu lists by using arrow keys as well, once you have used the TAB key to enter the menu. Usually the ENTER key activates a link, in some browsers this might be SPACEBAR instead. Mac OS X does not generally have this option available by default unless you are using a screen reader, but you can turn on keyboard navigation.
Can you see what link you are on? Can you determine where you are on the page? Does the TAB order make sense, when you click on TAB to navigate from link to link, is the order logical and easy to follow? Do you enter form fields? If you answer no to any of these questions, then your page has some accessibility issues such as Visible Focus or an improper tab order. This is also an important time to make sure you are using Descriptive Links, if you use the TAB key to navigate, does the link you are on make sense by itself?
It is always preferred that the tab order make sense through the design of the web site, put things in logical linear order. However, you can adjust the tab order using the HTML code tabindex. Using
<tabindex="number"> inside elements like links or form fields can let you adjust the tab order on the site. Tabindex can also be used on elements like
<div> to determine tab order, but remember that native, unadjusted tab order is always preferred and the best for accessibility.
Using a content management system like Drupal, much of the design is already taken care of for you, so you really only need to worry about content. You can still easily test the keyboard accessibility of your site using the methods above, but the tab order has in most cases already been defined. What you can do is decide where to lay out content on your site for the best access possible. Navigate your site and make sure it is in a logical linear order. If it is not, adjust blocks to find the best order.
<tabindex> option is available when you are creating links, under the "Advanced" tab. You can also edit the HTML and add this feature if so desired.