Accessibility Guide for WCAG 2.0 (A)
Makes certain that <input type="image">
elements have alternate text.
Screen reader users will not understand the function of a <input type="image">
button unless equivalent wording is provided. Even if the image merely contains text, alternate text is required because a screen reader cannot interpret images of words into output.
Simply typing text adjacent to the form element will not result in a true label. Screen readers, for example, require labels in code that can be determined automatically.
Some screen readers are configured to estimate the label based on the surrounding text, however this method is not foolproof and might cause confusion if the screen reader guesses incorrectly.
What this Accessibility Rule Checks
Ensures that each <input type="image">
has a name that can be found.
Each form element must have a label
element attached with it programmatically.
Forms must have effective form labels in order to be accessible. Form elements like as checkboxes, radio buttons, input fields, etc. are frequently self-explanatory to sighted users, even if they are not programmatically labeled. Users with screen readers require descriptive form labels to identify form fields. Adding labels to all form elements removes uncertainty and makes the product more accessible.
When form elements lack labels, screen reader users are unaware of the expected data input. Screen readers cannot determine information about input items programmatically in the absence of an established label association (or redundant text functioning as a label).
Since clicking the label activates the control, people with weak motor control do not benefit from a bigger clickable area for the control.
What this Accessibility Rule Checks
Ensures that each form element has a label associated with it programmatically.
Makes sure that people who can’t differentiate colors can tell when text is a link by checking that the link has either a distinct style that doesn’t depend on color or a contrast difference of more than 3:1, which tells you that manual testing is needed.
Some people with low vision have low contrast, which means there aren’t many bright or dark areas. Everything looks about the same brightness, which makes it hard to see details, edges, borders, and outlines. It can be hard to read text that is the same brightness as the background.
There are almost three times as many people with low vision as there are who are totally blind. One in twelve people, or about 8% of men and 0.4% of women in the US, has a color deficiency. People with low vision or color blindness can’t tell what the text is against a background that doesn’t have enough contrast.
When there isn’t a 3:1 color contrast between the color of the link text and the color of the text around it, people with low vision or low contrast can’t tell by looking that the text is meant to be a link.
What this Accessibility Rule Checks
Checks that all links in blocks of text have a color difference of at least 3:1 from the text around them, so that people who can’t tell the colors apart can still find the link.
This rule looks at some of the most common ways to tell a link from the text around it, such as underlining, font styling, a border, or a background. No rule has been broken if the link has its own style that doesn’t depend on color (pass). There is a violation if the link doesn’t have a clear style and the contrast is less than 3:1. (fail). When the link doesn’t have a distinct style and the contrast difference is 3:1 or higher, you must check that the link has a distinct style when you focus on it or hover over it. This can’t be reliably done by a computer, so you have to do it by hand.
When used as links, link text and alternative text for images must be recognizable by screen readers, have no duplicate labels, and be focusable.
- Accessibility is hindered by inaccessible link components, as they are a crucial component of a website.
- Users who traverse a webpage using only the keyboard (and no mouse) can only click on links that can gain programmed emphasis. Inaccessible to these users is any link that cannot gain programmatic focus.
- Similar to sighted people, screen reader users must know where a link leads. This information is provided via inner link text, albeit it will not be utilized if a screen reader cannot access it.
-
Only the links and form components that can get programmatic focus can be activated by keyboard users, including those with visual impairments or those who cannot use a mouse. Keyboard users cannot access events activated only by other sorts of focus, such as
onmouseover
events that depend on the mouse hover focus. By default, only links and form elements receive keyboard emphasis. Addtabindex="0"
to items that are not links or form components to make them focusable.
What this Accessibility Rule Checks
Ensures that each link’s name is accessible.
Lists must be correctly marked up, which means they cannot contain content components other than li
elements.
Lists are read aloud in a specific manner by screen readers. This feature makes lists easier to comprehend, but it will only function if the lists are correctly organized.
When content elements other than list items are contained within a set of list elements, screen readers are unable to indicate to the user that they are listening to list items.
Any other content elements are invalid.
Although non-content elements such as script
, template
, style
, meta
, link
, map
, area
, and datalist
are allowed in lists, content elements other than li
are not.
What this Accessibility Rule Checks
Ensures that lists are properly constructed.
All list items (li
) must have ul
or ol
parent elements.
To be considered valid, a list must have both parent and child entries. Element parents may consist of either a set of ul
or ol
tags. Within these tags, child elements must be declared using the li
tag.
Screen readers alert users when they arrive at a list and inform them of its length. Announcing the number of items in a list and the current item helps listeners understand what they are hearing and what to anticipate as they continue to listen.
If you do not mark up a list with the correct semantic markup in a hierarchy, list elements cannot alert the listener that they are listening to a list if no parent indicates the presence of a list and its type.
What this Accessibility Rule Checks
Ensures li
elements are used in a semantic way.
Elements of type <marquee>
are prohibited because they are deprecated, add difficulty for users with limited dexterity, and distract users with cognitive or attention problems.
The marquee
element produces difficult-to-read and-click-on scrolling text. Furthermore, it can be disturbing to viewers, particularly those with low eyesight, cognitive impairments, or concentration difficulties.
People with attention difficulties or cognitive impairments may be distracted by scrolling content. People with inadequate fine motor skills may not be able to precisely click on links inside scrolling content. Users with visual impairments may not be able to read the content of the scrolling text with sufficient clarity.
What this Accessibility Rule Checks
Prevents the use of the deprecated marquee
element.
The document must not use <meta http-equiv="refresh">
with a refresh time of less than 20 hours, as this could prohibit users with disabilities from controlling when the page is refreshed.
Since consumers do not anticipate a page to immediately reload, this behavior might be unsettling. Reloading also returns the programmatic emphasis to the page’s top, away from where the user had it. Such resets are irritating to users.
Redirection and page refresh via the <meta>
element are problematic for users with impairments in a number of ways. Redirects and refreshes are problematic for the primary reason that the user has no control over when they occur. If the objective of the <meta>
element is to redirect the user to a new location, server-side rather than client-side procedures should be implemented. Moving or auto-updating content might be a hindrance for those who have problems reading stationary material fast and for those who have trouble monitoring moving objects. It can also present difficulties for screen readers.
What this Accessibility Rule Checks
Examines whether the http-equiv="refresh"
attribute is present on meta
elements with a content
value of less than 20 hours.
Screen readers do not announce nested interactive controls.
Screen readers do not notify focusable components with interactive control ancestors (any element that accepts user input, such as buttons or anchor elements) and they produce an empty tab stop. In other words, even if you tab to the element, the screen reader won’t say its name, function, or status.
What this Accessibility Rule Checks
Ensure that no focusable child elements are present in any interactive controls.
Ensures that video
or audio
elements don’t have autoplay audio that lasts more than three seconds without a way to silence it.
When using screen reading software, people who are blind or have low vision may have trouble hearing the screen reader’s spoken output if other audio is playing at the same time.
If automatically playing audio continues for more than three seconds, it must be possible to pause, stop, or adjust the level using a well placed, easily accessible mechanism.
Users of screen readers can hear the screen reader without any other sounds playing thanks to an audio control.
A screen reader user’s ability to find the stop button may be hampered if audio starts playing immediately when they land on a page. This is because they navigate by listening, and automatically starting sounds may obstruct that navigation.
Therefore, we oppose the practice of automatically starting sounds (especially if they run longer than three seconds) and encourage users to start the sound themselves once they arrive at the page rather than expecting them to stop the sound themselves once they have reached the page.
What this Accessibility Rule Checks
The algorithm for this rule returns:
-
Undefined when
<audio>
has no source (duration cannot be interpreted). -
Undefined when
<video>
has no source (duration cannot be interpreted). -
False when
<audio>
can autoplay and has no controls mechanism. -
False when
<video>
can autoplay and has no controls mechanism -
False when
<audio>
plays less than three seconds but loops. -
True when
<video>
can autoplay and duration is less than three seconds (by passing options). -
True when
<video>
can autoplay and duration is below allowed duration (by setting playback range). -
True when
<audio>
can autoplay but has controls mechanism. -
True when
<video>
can autoplay and has controls mechanism.