Use unique IDs for ARIA references

Rule Details

ARIA attributes like aria-labelledby, aria-describedby, and aria-controls rely on element IDs to create relationships. If these IDs are not unique, the relationships become ambiguous and unreliable.

Code Example

<!-- ✅ Good: Unique IDs for ARIA mapping -->
<h2 id="modal-title-1">Settings</h2>
<div role="dialog" aria-labelledby="modal-title-1">...</div>
 
<!-- ❌ Bad: Duplicate IDs referenced by ARIA -->
<div id="desc">Standard shipping</div>
<button aria-describedby="desc">Option A</button>
 
<div id="desc">Express shipping</div>
<button aria-describedby="desc">Option B</button> <!-- Error: Screen reader may only see the first "desc" -->

Why It Matters

• Accurate Labeling: Screen readers use these references to announce labels and descriptions. Duplicates cause the wrong text to be read.
• Dynamic Interaction: aria-controls helps users understand which part of the page changes when they interact with a toggle or menu.
• Relationship Clarity: Clear ID mapping ensures that users with disabilities receive the same contextual information as sighted users.

Best Practices

✅ Unique Reference IDs: Ensure that every element used as a label or description source has a globally unique ID. ✅ Validation: Use tools that specifically check the "Accessibility Tree" to ensure references are resolving correctly. ✅ Dynamic IDs: If generating content dynamically, use a library or utility to ensure generated IDs are unique (e.g., useId in React).

Tools & Validation

• Axe-core Rule: duplicate-id-aria (opens in new tab)
• Accessibility Insights for Web (opens in new tab)

Exceptions

• Prefer native HTML semantics over ARIA when both are possible; some apparent ARIA failures disappear when the underlying element is corrected.
• A missing ARIA attribute is not automatically the strongest finding if the control is already semantically broken, unnamed, or keyboard-inaccessible.
• Do not add ARIA only to satisfy the rule if the feature should instead be implemented with a native element or a simpler interaction pattern.

Standards

• Align the implementation with WAI-ARIA 1.2 and verify the rendered experience, not only the source code.
• Align the implementation with MDN: ARIA and verify the rendered experience, not only the source code.

Verification

Automated Checks

• Inspect the browser accessibility tree or accessibility pane for the relevant element, role, or accessible name.
• Run an automated accessibility checker such as axe or Lighthouse where applicable.

Manual Checks

• Test the affected UI with keyboard-only navigation and confirm the rule holds in the rendered experience.
• Re-test one representative user flow with a screen reader if this rule affects a key interaction.