Use correct list structure

Rule Details

HTML list elements such as <ul> (opens in new tab) and <ol> have a specific requirement: their only direct children must be <li> elements (or <script> and <template> elements). The HTML standard (opens in new tab) makes that structure explicit, so placing other tags like <div> directly inside a list breaks the semantics.

Code Example

<!-- Incorrect: Direct child is a div -->
<ul>
  <div>
    <li>Item 1</li>
    <li>Item 2</li>
  </div>
</ul>
 
<!-- Correct: All children are li elements -->
<ul>
  <li>Item 1</li>
  <li>Item 2</li>
  <li>
    <!-- Nested lists must be inside an li -->
    <ul>
      <li>Sub-item 1</li>
    </ul>
  </li>
</ul>

Why It Matters

• Assistive Technology Interpretation: Screen readers announce "List of 3 items" when entering a list. Incorrect structure can cause the list to be miscounted or ignored entirely.
• Markup Validation: Breaking the parent-child relationship of lists makes the HTML invalid, which can lead to unpredictable rendering issues.
• Consistency: Users expect standard list behavior (like bullet points and numbering) which is best achieved through standard markup.
• Search Engine Parsing: Search engines use the structure of your lists to understand relationships between pieces of content.

Exceptions

• Simple data tables can sometimes fail more from missing header relationships than from missing enhancements such as captions or mobile wrappers, so prioritize the strongest semantic issue.
• Do not convert layout structures into data-table markup just to satisfy a rule; the correct fix may be to remove table semantics entirely.
• When several table-accessibility issues overlap, resolve the header-cell relationship first because downstream announcements depend on it.

Standards

• Align the implementation with W3C WAI: WCAG Overview and verify the rendered experience, not only the source code.
• Align the implementation with MDN: Accessibility 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.