attr-lowercase

Attribute name must be lowercase.

Level: Error

Config value

• true: enable rule
• false: disable rule
• ['fooBar', 'Test']: enable rule except for the given attribute names. All SVG camelCase properties are included, for example viewBox

Example

{
  ...
  "attr-lowercase": ['fooBar']
  ...
}

The following pattern is not considered a rule violation:

<img src="test.png" alt="test" />

<!-- known SVG attributes are ignored -->
<svg width="200" height="200" viewBox="0 0 200 200" />

The following pattern is considered a rule violation:

<img SRC="test.png" ALT="test" />

Why this rule is important

Lowercase attribute names are required for HTML5 compliance and to ensure consistency across different HTML elements.