Rules

Conformance checking

Rule ID	Description
attr-duplication	Warns that attributes were duplicated in one element. Capital letters and lower-case letters are not distinguished.
deprecated-attr	Warns when there is an attribute defined as deprecated or obsolete.
deprecated-element	Warns when there is an element defined as deprecated or obsolete or non-standard.
disallowed-element	Warns if specified elements appear on a document or an element.
doctype	Warns when doesn't including DOCTYPE.
heading-levels	Warns for skipped heading levels
id-duplication	Warns that id attribute value were duplicated in one document.
invalid-attr	Warn if an attribute is a non-existent attribute or an invalid type value due to the specifications (or the custom rule).
no-duplicate-dt	No duplicate names in <dl>
no-empty-palpable-content	Warn if there is an empty palpable content element.
no-orphaned-end-tag	Warns when an end tag appears without a corresponding start tag, which constitutes an inner parse error in HTML Standard.
permitted-contents	Warn if a child element has a not allowed element or text node.
placeholder-label-option	Checking whether the select element needs the placeholder label option.
require-datetime	Warn to need the datetime attribute if the time element has invalid content.
required-attr	Warns if specified attributes or required attribute on specs are not appeared on an element.
required-element	Required elements

Accessibility

Rule ID	Description
label-has-control	Warns if the label element has no control.
landmark-roles	Whether banner, main, complementary and contentinfo are top-level landmarks. Whether a specific landmark roll has unique label when used multiple times on a page
neighbor-popovers	Warns when popover triggers and their corresponding targets are not adjacent
no-ambiguous-navigable-target-names	Prevents typographical errors in links and more that could inadvertently replace special navigational keywords (_blank, _self, _parent, _top) with invalid target names, ensuring navigations behave as intended.
no-consecutive-br	Warns against the use of consecutive <br> tags
no-refer-to-non-existent-id	Check whether the ID or the list of ID specified to for, form, aria-*, and more, or a fragment in a hyperlink are referencing it that existed in the same document.
require-accessible-name	Warn if the element has no accessible name.
required-h1	Warn if there is no h1 element in the document.
table-row-column-alignment	Checks for consistency in the defined number of rows and columns.
use-list	Prompt to use list element when a bullet character is at the start of a text node.
wai-aria	Warn if the role attribute and aria-* attributes don't set in accordance with specs that are WAI-ARIA and ARIA in HTML.

Naming Convention

Rule ID	Description
class-naming	Warn if the class name does not conform to the specified rules.

Maintainability

Rule ID	Description
no-hard-code-id	Warn it hard-coded the value of the id attribute when the element is a fragment.
no-use-event-handler-attr	Warn when specifying the event handler attribute.

Style

Rule ID	Description
attr-value-quotes	Warns if the attribute value is not quoted.
case-sensitive-attr-name	Warns that the attribute name is not in one of uppercase or lowercase letters.
case-sensitive-tag-name	Warns that the tag name is not in one of uppercase or lowercase letters.
character-reference	Warns when unauthorized illegal characters are not escaped with character reference in the text node or attribute value.
end-tag	Warn if there is not an end tag.
ineffective-attr	Warn that if the attribute specified cannot affect (in other words, mean-less) the element.
no-boolean-attr-value	Warn when it specified any value to the boolean attribute.
no-default-value	Warn when it specifies the default value to the attribute.

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Removed rules

Rule ID	Description	Drop
attr-equal-space-after	Spaces after the equal of attribute	Since v3.0
attr-equal-space-before	Spaces before the equal of attribute	Since v3.0
attr-spacing	Spaces between attributes	Since v3.0
indentation	Indentation	Since v3.0