Axe Core Guide
Links must be distinguishable without relying on color
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.
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Related Accessibility Rules
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.
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.
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.
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.
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.
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.
ARIA attributes must be used as specified for the element’s role.
Using ARIA attributes on elements where they are not expected can result in unpredictable behavior for assistive technologies. This can lead to a poor user experience for people with disabilities who rely on these technologies. It is important to follow the ARIA specification to ensure that assistive technologies can properly interpret and communicate the intended meaning of the content.
Some ARIA attributes are only allowed on an element under certain conditions. Different attributes have different limitations to them:
aria-checked: This should not be used on an HTML input element with type=”checkbox”. Such elements have a checked state determined by the browser. Browsers should ignore aria-checked in this scenario. Because browsers do this inconsistently, a difference between the native checkbox state and the aria-checked value will result in differences between screen readers and other assistive technologies.
The aria-posinset, aria-setsize, aria-expanded, and aria-level attributes are conditional when used on a row. This can be either tr element, or an element with role="row". These attributes can only be used when the row is part of treegrid. When used inside a table or grid, these attributes have no function, and could result in unpredictable behavior from screen readers and other assistive technologies.
What this Accessibility Rule Checks
Check that ARIA attributes are not used in a way that their role describes authors should not, or must not do. I.e the use of this ARIA attribute is conditional.
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.
Elements must only use permitted ARIA attributes.
Using ARIA attributes in roles where they are prohibited can mean that important information is not communicated to users of assistive technologies. Assistive technologies may also attempt to compensate for the issue, resulting in inconsistent and confusing behavior of these tools.
Not all ARIA role-attribute combinations are valid. This Rule checks that noe of the attributes used with a particular role are listed as “prohibited” for that role in the latest version of WAI-ARIA.
The aria-label and aria-labelledby attributes are prohibited on presentation and none roles, as well as on text-like roles such as code, insertion, strong, etc.
What this Accessibility Rule Checks
Checks that each ARIA attribute used is not described as prohibited for that element’s role in the WAI-ARIA specification.