duplicate-id

Ensure that the id attribute values are unique.

Description

To avoid assistive technology overlooking the second instance where the same id value is used, ensure that the assigned value for the id attribute is unique.

Why is it important?

Having duplicate id values is a frequently encountered validation error that can lead to unexpected behavior in scripting and assistive technologies. This issue can compromise both the functionality and accessibility of a website or application. When multiple elements have the same id, screen readers will only recognize the first element and skip the subsequent ones. As a result, users will miss out on the complete content.

Examples

• Success:

  • Screen Readers reliably treat two <form> elements with different id values as separate entities.

• Failure:

  • Screen readers producing unpredictable results when two <form> elements have the same id values.

How to fix?

Ensure that the page is free from any duplicate “id” values and remove any duplicates if they are present.

Tags

cat.parsing, wcag2a, wcag411

References

• WCAG 4.1.1: Parsing
• WCAG 2.1 Technique H64
• Deque University: duplicate-id
• Accessibility Insights: duplicate-id
• Evinced Digital Accessibility Knowledge Base: duplicate-id