id must be unique

Rule ID Control 5
Definition All id attribute values must be unique on the page.
Purpose
  • id attribute values on form control elements can be used as references by label elements. When id attribute values on the page are not unique, form controls may be incorrectly labelled.
  • aria-labelledby and aria-describedby atributes also depend on unique id values for labeling and adding descriptions to form controls.
Mappings
  • HTML4 Legacy Techniques (Required)
  • HTML5 and ARIA Techniques (Required)
WCAG Success Criteria

4.1.1 Parsing (Level A, Primary Success Criterion)

Other Related Success Criterion:

Rule Category Forms
Scope Element
Target Resources Form control elements with id attributes
  • select
  • textarea
Techniques
  • If a form control defines an id attribute, ensure that its value is unique on the page.
Informational Links