accessibility-guidelines

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Valid HTML

Make sure the HTML does not contain markup errors that are known to cause conflicts with assistive technologies (such as incorrect nesting of elements, or duplicate ids).


On this page:


Requirements

Common mistakes

Why?

This ensures that content and functionality is presented in a way that works reliably across all supported browsers and assistive technologies.

Official wording in the Web Content Accessibility Guidelines

4.1.1 Parsing: In content implemented using markup languages, elements have complete start and end tags, elements are nested according to their specifications, elements do not contain duplicate attributes, and any IDs are unique, except where the specifications allow these features. (Level A)

See the W3C’s detailed explanation of this guideline with techniques and examples.


Guidance for Web

Checking whether elements with ARIA role attributes are nested correctly

More guidance for Web


More info

Sources

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This document is in beta. Help us by reporting issues via Github or email.