Image elements do not have [alt] attributes that are redundant text
Image alt text does not duplicate the surrounding visible text.
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Impact
About
Informative elements should aim for short, descriptive alternative text. Alternative text that is exactly the same as the text adjacent to the link or image is potentially confusing for screen reader users, because the text will be read twice.
Risks
Screen reader users cannot identify or interact with elements.
Why it's important
Gives screen reader users meaningful descriptions of interactive elements so they can understand and use them.
User stories
As a screen reader user, I want all interactive elements to have clear, descriptive names so that I know what they do.
Code
Failing pattern:
<!-- Fail: alt text repeats surrounding caption -->
<figure>
<img src="photo.jpg" alt="White House photo">
<figcaption>White House photo</figcaption>
</figure>
Passing pattern:
<!-- Pass: alt is empty when caption already describes the image -->
<figure>
<img src="photo.jpg" alt="">
<figcaption>The White House, 1600 Pennsylvania Ave NW, Washington, DC</figcaption>
</figure>
Error
ScanGov messaging when a site fails a standard:
Failed: Image elements do not have [alt] attributes that are redundant text
Guidance
Indicators
Related
- [accesskey] values are unique
- [aria-*] attributes match their roles
- Uses ARIA roles only on compatible elements
- button, link, and menuitem elements have accessible names
- ARIA attributes are used as specified for the element's role
- Deprecated ARIA roles were not used
- Elements with role="dialog" or role="alertdialog" have accessible names
- [aria-hidden="true"] is not present on the document <body>
- [aria-hidden="true"] elements do not contain focusable descendents
- ARIA input fields have accessible names
- ARIA meter elements have accessible names
- ARIA progressbar elements have accessible names
- Elements use only permitted ARIA attributes
- [role]s have all required [aria-*] attributes
- Elements with an ARIA [role] that require children to contain a specific [role] have all required children
- [role]s are contained by their required parent element
- [role] values are valid
- Elements with the role=text attribute do not have focusable descendents
- ARIA toggle fields have accessible names
- ARIA tooltip elements have accessible names
- ARIA treeitem elements have accessible names
- [aria-*] attributes have valid values
- [aria-*] attributes are valid and not misspelled
- Buttons have an accessible name
- The page contains a heading, skip link, or landmark region
- Background and foreground colors have a sufficient contrast ratio
- <dl>'s contain only properly-ordered <dt> and <dd> groups, <script>, <template> or <div> elements
- Definition list items are wrapped in <dl> elements
- Document has a <title> element
- ARIA IDs are unique
- No form fields have multiple labels
- <frame> or <iframe> elements have a title
- Heading elements appear in a sequentially-descending order
- <html> element has a [lang] attribute
- <html> element has a valid value for its [lang] attribute
- <html> element has an [xml:lang] attribute with the same base language as the [lang] attribute
- Image elements have [alt] attributes
- Input buttons have discernible text
- <input type="image"> elements have [alt] text
- Form elements have associated labels
- Links are distinguishable without relying on color
- Links have a discernible name
- Lists contain only <li> elements and script supporting elements (<script> and <template>)
- List items (<li>) are contained within <ul>, <ol> or <menu> parent elements
- The document does not use <meta http-equiv="refresh">
- [user-scalable="no"] is not used in the <meta name="viewport"> element and the [maximum-scale] attribute is not less than 5
- <object> elements have alternate text
- Select elements have associated label elements
- Skip links are focusable
- No element has a [tabindex] value greater than 0
- Tables have different content in the summary attribute and <caption>
- Touch targets have sufficient size and spacing
- Cells in a <table> element that use the [headers] attribute refer to table cells within the same table
- <th> elements and elements with [role="columnheader"/"rowheader"] have data cells they describe
- [lang] attributes have a valid value
- <video> elements contain a <track> element with [kind="captions"]
- All heading elements contain content
- Identical links have the same purpose
- Document has a main landmark
- Elements with visible text labels have matching accessible names
- Tables use <caption> instead of cells with the [colspan] attribute to indicate a caption
- <td> elements in a large <table> have one or more table headers
- Image aspect ratio
- Valid doctype
- Character encoding
- Accessibility grades on Project ScanGov
- ScanGov Accessibility
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