Matan · WCAG · Robust

Unique IDs

WCAG 4.1.1 (and good HTML): id values must be unique in a document.

Pass condition in our engine: No duplicate id attributes on the page.

1. Problem description

Duplicate ids break label for=, aria-labelledby, skip links and fragment navigation. They often come from repeating a widget without namespacing ids.

2. Most common causes

  • A slider partial included three times with id="slide".
  • Server-rendered lists using a constant id.

3. How to fix it

  1. Generate unique ids (include an index or entity id).
  2. Prefer classes for styling, ids only when you must target one node.

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