Disallows elements with duplicated ID

Rule ID:

no-dup-id

Category:

Document

Standards:

• HTML5

The ID of an element must be unique within the document. When <template> is used the id within the template must be unique but can otherwise contain duplicates as it isn't attached to the document yet.

Rule details

Examples of incorrect code for this rule:

<div id="foo"></div>
<div id="foo"></div>

error: Duplicate ID "foo" (no-dup-id) at inline:2:10:
  1 | <div id="foo"></div>
> 2 | <div id="foo"></div>
    |          ^^^


1 error found.

Examples of correct code for this rule:

<div id="foo"></div>
<div id="bar"></div>