HTML Rules

Below the list of rules supported by Biome, divided by group. Here’s a legend of the emojis:

The icon indicates that the rule is part of the recommended rules.
The icon indicates that the rule provides a code action (fix) that is safe to apply.
The icon indicates that the rule provides a code action (fix) that is unsafe to apply.
The icon indicates that the rule has been implemented and scheduled for the next release.

`a11y`

| Rule name | Description | Properties | | --- | --- | --- | | noAccessKey | Enforce that the accesskey attribute is not used on any HTML element. | | | noAutofocus | Enforce that the autofocus attribute is not used on elements. | | | noDistractingElements | Enforces that no distracting elements are used. | | | noHeaderScope | The scope prop should be used only on <th> elements. | | | noPositiveTabindex | Prevent the usage of positive integers on tabindex attribute. | | | noRedundantAlt | Enforce img alt prop does not contain the word “image”, “picture”, or “photo”. | | | noSvgWithoutTitle | Enforces the usage of the title element for the svg element. | | | useAltText | Enforce that all elements that require alternative text have meaningful information to relay back to the end user. | | | useAnchorContent | Enforce that anchors have content and that the content is accessible to screen readers. | | | useAriaPropsForRole | Enforce that elements with ARIA roles must have all required ARIA attributes for that role. | | | useButtonType | Enforces the usage and validity of the attribute type for the element button | | | useHtmlLang | Enforce that html element has lang attribute. | | | useIframeTitle | Enforces the usage of the attribute title for the element iframe. | | | useMediaCaption | Enforces that audio and video elements must have a track for captions. | | | useValidAriaRole | Elements with ARIA roles must use a valid, non-abstract ARIA role. | | | useValidLang | Ensure that the attribute passed to the lang attribute is a correct ISO language and/or country. | |

`nursery`

| Rule name | Description | Properties | | --- | --- | --- | | noAmbiguousAnchorText | Disallow ambiguous anchor descriptions. | | | noDuplicateAttributes | Disallow duplication of attributes. | | | noInlineStyles | Disallow the use of inline styles. | | | noScriptUrl | Disallow javascript: URLs in HTML. | | | noSyncScripts | Prevent the usage of synchronous scripts. | | | noVueVIfWithVFor | Disallow using v-if and v-for directives on the same element. | | | noVueVOnNumberValues | Disallow deprecated number modifiers on Vue v-on directives. | | | useIframeSandbox | Enforce the ‘sandbox’ attribute for ‘iframe’ elements. | | | useScopedStyles | Enforce that <style> blocks in Vue SFCs have the scoped attribute and that <style> blocks in Astro components do not have the is:global directive. | | | useVueConsistentVBindStyle | Enforce a consistent style for v-bind in Vue templates. | | | useVueConsistentVOnStyle | Enforce a consistent style for v-on in Vue templates. | | | useVueHyphenatedAttributes | Enforce hyphenated (kebab-case) attribute names in Vue templates. | | | useVueVForKey | Enforce that elements using v-for also specify a unique key. | | | useVueValidTemplateRoot | Enforce valid Vue <template> root usage. | | | useVueValidVBind | Forbids v-bind directives with missing values or invalid modifiers. | | | useVueValidVCloak | Enforce valid v-cloak Vue directives. | | | useVueValidVElse | Enforce valid usage of v-else. | | | useVueValidVElseIf | Enforce valid v-else-if directives. | | | useVueValidVFor | Enforces valid v-for directives in Vue templates. | | | useVueValidVHtml | Enforce valid v-html directives. | | | useVueValidVIf | Enforces valid v-if usage for Vue templates. | | | useVueValidVOn | Enforce valid v-on directives with proper arguments, modifiers, and handlers. | | | useVueValidVOnce | Enforce valid v-once Vue directives. | | | useVueValidVPre | Enforce valid v-pre Vue directives. | | | useVueValidVText | Enforce valid v-text Vue directives. | | | useVueVapor | Enforce opting in to Vue Vapor mode in <script setup> blocks. | |

Recommended rules

noAccessKey (Severity: error)
noAutofocus (Severity: error)
noDistractingElements (Severity: error)
noHeaderScope (Severity: error)
noPositiveTabindex (Severity: error)
noRedundantAlt (Severity: error)
noSvgWithoutTitle (Severity: error)
useAltText (Severity: error)
useAnchorContent (Severity: error)
useAriaPropsForRole (Severity: error)
useButtonType (Severity: error)
useHtmlLang (Severity: error)
useIframeTitle (Severity: error)
useMediaCaption (Severity: error)
useValidAriaRole (Severity: error)
useValidLang (Severity: error)

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