Accessibility Guide for WCAG 2.0 (A)
An image map consists of a single image with numerous clickable sections. Because screen readers cannot translate graphics into text, an image map, like all images, must contain alternate text for each of the distinct clickable parts, as well as for the larger image itself.
In the absence of alternate text, screen readers often announce the image’s filename. Filenames do not accurately describe images and are therefore inconvenient for screen reader users.
What this Accessibility Rule Checks
Ensures that image map area elements have alternate text.
Not all ARIA role-attribute combinations are valid. This rule ensures that each role has the required qualities.
Using ARIA attributes in roles where they are not permitted can impair web page accessibility. Using an improper role-attribute combination will have no effect on application accessibility at best and may trigger behavior that blocks accessibility for entire areas of an application at worst.
When ARIA attributes are used on HTML elements that do not conform to WAI-ARIA 1.1, they interfere with the semantics of the elements, causing assistive technology products to display nonsensical user interface (UI) information that does not represent the document’s true UI.
What this Accessibility Rule Checks
Checks that each element with an ARIA role is using only the ARIA attributes that are permitted for that role.
The destination, purpose, function, or action of an ARIA command element must be made clear in understandable text for screen reader users.
The function of items with the roles link, button, or menuitem that lack an accessible name cannot be understood by screen reader users.
What this Accessibility Rule Checks
Verifies that all elements with the roles link, button, or menuitem have a clear, understandable name.
The content of the document is inaccessible to assistive technologies if <body aria-hidden="true"> is present.
Applying aria-hidden="true" to objects that are otherwise accessible: A web page is supposed to be fully accessible, and it would be accessible if elements lacked the aria-hidden="true" attribute value. Screen readers do not read information tagged with the property value aria-hidden="true". Users may continue to tab to focusable items within the hidden objects, but screen readers will stay mute.
Any purposefully hidden information or interface elements, such as dormant dialogs and collapsed menus, must also be hidden from screen reader users. When items are accessible to sighted people, such as when they engage a button or expand a menu item, they must also be accessible to users of screen readers.
The objective is to give screen reader users with an experience comparable to that of sighted users. If there is a strong reason to hide something from visible users, there is typically a compelling one to hide it from blind users as well. When content is made accessible to sighted people, it makes sense to also make it accessible to blind users.
What this Accessibility Rule Checks
Checks for the presence of the ‘aria-hidden=”true”‘ attribute on the ‘body’ element of the document and returns a message indicating success or failure.
This rule determines whether or not aria-hidden elements contain focusable elements.
Using the property aria-hidden="true" on an element removes the element and all of its child nodes from the accessibility API, rendering the element fully unavailable to screen readers and other assistive technology.
aria-hidden may be used with extreme discretion to hide visibly displayed content from assistive technologies if the act of hiding this content is meant to enhance the experience of assistive technology users by reducing redundant or superfluous content.
If aria-hidden is employed to hide material from screen readers, the same or equal meaning and functionality must be made available to assistive technologies.
Using aria-hidden="false" on content that is a descendant of an element that is hidden using aria-hidden="true" will not reveal that content to the accessibility API, nor will it be accessible to screen readers or other assistive technology.
The rule applies to any element whose aria-hidden attribute value is true.
By adding aria-hidden="true" to an element, authors assure that assistive technologies will disregard the element.
This can be used to hide aesthetic elements, such as icon typefaces, that are not intended to be read by assistive technologies.
A focusable element with aria-hidden="true" is disregarded as part of the reading order, but is still part of the focus order, making it unclear if it is visible or hidden.
What this Accessibility Rule Checks
For all user interface components, including form elements, links, and script-generated components, the name and role can be identified programmatically; user-specified states, properties, and values can be set programmatically; and user agents, including assistive technologies, are notified of changes.
Ensures every ARIA input field has an accessible name.
This rule ensures that each ARIA input field has a name that is accessible.
There must be accessible names for the following input field roles:
- combobox
- listbox
- searchbox
- slider
- spinbutton
- textbox
What this Accessibility Rule Checks
The names of ARIA input fields must be accessible.
For screen reader users, aria meter elements must have legible language that defines the destination, function, or action.
Users of screen readers are unable to determine the function of items with role="meter" but no accessible name.
What this Accessibility Rule Checks
Checks that all items with role="meter" have a distinguishable, accessible name.
For screen reader users, Aria progressbar items must include understandable language that specifies the destination, purpose, or action.
Users of screen readers are unable to determine the purpose of items with the role="progressbar" attribute that lack an accessible name.
What this Accessibility Rule Checks
Checks that all items with role="progressbar" have a distinguishable, accessible name.
ARIA widget roles must contain attributes describing the widget’s state or properties.
ARIA widget roles necessitate additional properties describing the widget’s state. If a needed attribute is missing, the widget’s status is not conveyed to users of screen readers.
Some roles function as composite user interface widgets. As such, they serve as containers that manage the widgets they contain. When an object inherits from several ancestors and one ancestor indicates support for a property and another says the property is required, the property becomes required on the inheriting object. In some circumstances, default values are sufficient to meet ARIA attribute requirements.
When required state and property attributes for specific roles (and subclass roles) are missing, screen readers may be unable to communicate the element’s role definition to the user.
What this Accessibility Rule Checks
Checks all elements with the role attribute to ensure that all necessary attributes are defined.
Some ARIA parent role values must contain specific child elements and role values in order to execute the intended accessibility function.
WAI-ARIA outlines specifically, for each role, which child and parent roles are permitted and/or required. ARIA roles lacking needed child roles will not be able to execute the desired accessibility functions.
The user’s context must be communicated by assistive technology. In a treeitem, for instance, it is essential to know the parent (container), item, and siblings in the folder. This is possible in two ways:
- Code order or DOM: The context required is frequently evident from the code order or DOM.
-
ARIA: ARIA (such as
aria-owns) can be used to provide relationships when the hierarchy differs from the code structure or the DOM tree.
What this Accessibility Rule Checks
Checks each element containing a WAI-ARIA role for the presence of all requisite child roles.
Certain ARIA roles must be enclosed by specific parent roles in order to carry out their intended accessibility functions.
WAI-ARIA outlines specifically, for each role, which child and parent roles are permitted and/or required. Elements with ARIA role values that lack needed parent element role values will prevent assistive technology from functioning as the developer intended.
When it is necessary to convey context to a user of assistive technology in the form of hierarchy (for example, the importance of a parent container, item, or sibling in a folder tree), and the hierarchy is not the same as the code structure or DOM tree, it is impossible to provide relationship information without using ARIA role parent elements.
What this Accessibility Rule Checks
Checks each WAI-ARIA role-containing element to confirm that all required parent roles are present.
Ensures that the aria-roledescription attribute is only applied to elements having explicit or implicit role values.
Inappropriate aria-roledescription attribute values that clash with an element’s implicit or explicit role value can impede the web page’s accessibility. A contradictory aria-roledescription attribute value may have no effect on the application’s accessibility and may trigger behavior that blocks accessibility for entire application sections.
When aria-roledescription attributes are applied to HTML elements not in accordance with WAI-ARIA 1.1, a semantic conflict may occur between the aria-roledescription value and the implicit or explicit element role value, resulting in assistive technology products reporting nonsensical user interface (UI) information that does not accurately represent the intended UI experience.
What this Accessibility Rule Checks
Use aria-roledescription values to adequately explain implicit or explicit element role values.
ARIA role values must be assigned valid values. Role values must be appropriately written, correlate to existing ARIA role values, and not be abstract roles in order to correctly display the element’s purpose.
Assistive technologies do not read elements with erroneous ARIA role values as intended by the developer.
When screen readers and other assistive devices do not know the function of each element on a web page, they are unable to interact with or communicate the function to the user. When a role value is invalid, an element’s characteristics, properties, and ways of transmitting information to and/or from the user can be communicated via assistive technologies.
What this Accessibility Rule Checks
Examines each element containing the WAI-ARIA role property to check that its value is valid.
Makes certain that each ARIA toggle field has an accessible name.
Ensures that any element having a semantic role has a name that is easily accessible.
Among the semantic roles are:
- checkbox
- menu
- menuitemcheckbox
- menuitemradio
- radio
- radiogroup
- switch
What this Accessibility Rule Checks
There is an accessible name for ARIA toggle fields.
Screen reader users are required to have access to understandable text within Aria tooltip elements. This text must define the destination, purpose, function, or action in a clear and concise manner.
Users of screen readers are unable to understand the function of elements that have the role of tooltip but do not have accessible names.
What this Accessibility Rule Checks
Performs a check on all elements that have the role tooltip to ensure that they have a name that can be understood and is accessible.
Valid values must be present for ARIA properties that begin with aria-.
To fulfill the intended accessibility purpose, these values must be written correctly and relate to values that make sense for a certain property.
ARIA attributes (those beginning with aria-) must have legitimate values. For a given attribute to fulfill the intended accessibility function, these values must be written correctly and correlate to values that make sense.
A diverse range of values are accepted for many ARIA attributes. There must be permitted values, acceptable “undefined” values, and acceptable “default” values.
Content that does not adhere to the permitted values is inaccessible to users of assistive technology.
What this Accessibility Rule Checks
Verifies that the WAI-ARIA attributes’ values are correct for each element that contains them.
The names of ARIA attributes beginning with “aria-“ must be correct.
A reference to an invalid attribute or an attribute that doesn’t exist will result in a violation of this rule.
The accessibility function intended by the developer will not be fulfilled if the developer uses an invalid or misspelled ARIA attribute.
User interface components meant to increase the accessibility and interoperability of web and application content must adhere to properly worded and up-to-date ARIA properties in order for assistive technology to provide suitable information to people with disabilities.
Insufficient usage of the WAI-ARIA 1.1 W3C Recommendation’s attributes prevents developers from correctly communicating user interface actions and structural information to assistive technology in document-level markup.
What this Accessibility Rule Checks
Verifies that all elements that contain WAI-ARIA attributes have those attributes and that they are legitimate attributes.
Make sure that the kind attribute in the track element is set to captions. Also, verify that the text content of the captions adequately communicates all relevant information from the audio element, including speaker identification, dialogue transcripts, musical cues, and sound effects.
Below is an example code that demonstrates the addition of two tracks, one in English and another in Spanish.
<audio>
<source src="conversation.mp3" type="audio/mp3">
<track src="captions_en.vtt" kind="captions" srclang="en" label="english_captions">
<track src="captions_es.vtt" kind="captions" srclang="es" label="spanish_captions">
</audio>What this Accessibility Rule Checks
Checks the use of all HTML5 <audio> elements to ensure each contains a <track> element with the kind attribute value captions.
This rule demands the absence of any blink elements. Blinking items might be challenging to activate, and flashing writing can be challenging to read.
The blink tag causes information to blink, as the name implies. Although you might enjoy the appearance, blinking text and objects (such as links and buttons) might be challenging to read and operate, especially for people with poor hand-eye coordination or limited dexterity.
For those who have visual or cognitive impairments, reading blinking letters can be quite challenging. Text that blinks can be annoying, especially for people who have cognitive difficulties. Some people may find it challenging to understand. The blink element should never be used due to these reasons.
What this Accessibility Rule Checks
Verifies that the blink element is never utilized.
For screen reader users, buttons must include recognizable text that specifies the destination, purpose, function, or action.
Users of screen readers are unable to determine the function of elements with the roles role="link", role="button", and role="menuitem" that lack an accessible name.
What this Accessibility Rule Checks
Verifies that each button has a distinguishable, accessible label.
Each page must have a main landmark to allow users to rapidly traverse repetitive blocks of material or interface elements (such as the header and navigation) and get the primary content.
Due to the fact that websites frequently display secondary, repetitive content on several pages (such as navigation links, heading graphics, and advertising frames), keyboard-only users benefit from faster, more direct access to a page’s principal content. This saves keystrokes and reduces physical discomfort.
It is more difficult and time-consuming for users who cannot use a mouse to navigate using the keyboard if the interface does not provide features to facilitate keyboard navigation. To activate a link in the middle of a web page, for instance, a keyboard user may have to browse through a significant number of links and buttons in the page’s header and primary navigation.
Extremely motor-impaired users may require several minutes to browse through all of these pieces, which can cause to tiredness and potential physical pain for some users. Even users with less severe limitations will require more time than users with a mouse, who can click on the desired link in less than a second.
What this Accessibility Rule Checks
Checks for the presence of at least one of the following features:
- an internal skip link
- a header
- a geographical landmark
Definition lists (dl) may only contain dt and dd groups, div, script, or template elements that are properly organized.
Screen readers have a particular method for reading definition lists. When such lists are not correctly marked up, screen reader output may be erroneous or confusing.
A list of definitions is used to explain the meaning of words or phrases. Using the dl element, the definition list is formatted. Within the list, each term is enclosed in its own dt element, and its definition is enclosed in the dd element that immediately follows.
What this Accessibility Rule Checks
Ensures that each dl element is correctly constructed.
To be valid, definition list items (dt and / or dd) must be enclosed by parent dl elements. This allows screen reader users to recognize the right hierarchy of the list’s information.
A definition list item is invalid if it is not surrounded by parent dl elements.
A definition list must adhere to a particular hierarchy. Using the dl element, a list is defined. It is followed by alternating sets of dt and dd elements, beginning with dt. dt elements define a term while dd elements denote a term’s description. Each group of dt components must be accompanied by a group of dd elements. In the definition list, only dt and dd items are permitted. If not followed, this hierarchy will render the list invalid.
What this Accessibility Rule Checks
Ensures that every child dd and dt element has a parent dl element.
The title element of the HTML document must not be empty in order to give users with an overview of its content.
Users using screen readers utilize page titles to obtain an overview of the page’s content. If a page lacks a title, navigating through it can soon become difficult and confusing for screen reader users. The title element of the page is the first item screen reader users hear when the page loads.
When they arrive at a page, screen reader users hear the page’s title first. If there is no title or if the title is not descriptive and unique, users of screen readers must read the page to discern its content and purpose.
What this Accessibility Rule Checks
Makes certain that each HTML document has a title tag associated with it.
The value supplied to active ID attributes on focusable elements must be unique to avoid assistive technology from overlooking the second instance. Active ID attributes may not be used more than once on focusable components inside the same document; assistive technology requires unique IDs for focusable active elements in order to differentiate between them.
Focusable components on a page are identified exclusively by the ID attribute. It is illogical to duplicate an active ID.
Duplicate active ID values compromise the accessibility of focusable elements, such as form labels, table header cells, and so on. Screen readers and client-side scripts will bypass all instances of repetition other than the first. Validating HTML files aids in preventing and eliminating potential sources of accessibility issues, so long as accessibility is not compromised.
Those who have expertise with client-side scripting are aware that when an active ID is reused, the only instance that is normally acted upon by the script is the first. Similarly, assistive technology may only appropriately reference the first active ID when mentioning it.
What this Accessibility Rule Checks
Ensures that each page element with an active ID and a focusable state has a unique value.