Configuration

Enforce that the accessKey attribute is not used on any HTML element. See https://biomejs.dev/linter/rules/no-access-key

Enforce that aria-hidden="true" is not set on focusable elements. See https://biomejs.dev/linter/rules/no-aria-hidden-on-focusable

Enforce that elements that do not support ARIA roles, states, and properties do not have those attributes. See https://biomejs.dev/linter/rules/no-aria-unsupported-elements

Enforce that autoFocus prop is not used on elements. See https://biomejs.dev/linter/rules/no-autofocus

Enforces that no distracting elements are used. See https://biomejs.dev/linter/rules/no-distracting-elements

The scope prop should be used only on <th> elements. See https://biomejs.dev/linter/rules/no-header-scope

Enforce that non-interactive ARIA roles are not assigned to interactive HTML elements. See https://biomejs.dev/linter/rules/no-interactive-element-to-noninteractive-role

Enforce that a label element or component has a text label and an associated input. See https://biomejs.dev/linter/rules/no-label-without-control

Disallow use event handlers on non-interactive elements. See https://biomejs.dev/linter/rules/no-noninteractive-element-interactions

Enforce that interactive ARIA roles are not assigned to non-interactive HTML elements. See https://biomejs.dev/linter/rules/no-noninteractive-element-to-interactive-role

Enforce that tabIndex is not assigned to non-interactive HTML elements. See https://biomejs.dev/linter/rules/no-noninteractive-tabindex

Prevent the usage of positive integers on tabIndex property. See https://biomejs.dev/linter/rules/no-positive-tabindex

Enforce img alt prop does not contain the word "image", "picture", or "photo". See https://biomejs.dev/linter/rules/no-redundant-alt

Enforce explicit role property is not the same as implicit/default role property on an element. See https://biomejs.dev/linter/rules/no-redundant-roles

Enforce that static, visible elements (such as <div>) that have click handlers use the valid role attribute. See https://biomejs.dev/linter/rules/no-static-element-interactions

Enforces the usage of the title element for the svg element. See https://biomejs.dev/linter/rules/no-svg-without-title

Enables the recommended rules for this group

Enforce that all elements that require alternative text have meaningful information to relay back to the end user. See https://biomejs.dev/linter/rules/use-alt-text

Enforce that anchors have content and that the content is accessible to screen readers. See https://biomejs.dev/linter/rules/use-anchor-content

Enforce that tabIndex is assigned to non-interactive HTML elements with aria-activedescendant. See https://biomejs.dev/linter/rules/use-aria-activedescendant-with-tabindex

Enforce that elements with ARIA roles must have all required ARIA attributes for that role. See https://biomejs.dev/linter/rules/use-aria-props-for-role

Enforce that ARIA properties are valid for the roles that are supported by the element. See https://biomejs.dev/linter/rules/use-aria-props-supported-by-role

Enforces the usage of the attribute type for the element button. See https://biomejs.dev/linter/rules/use-button-type

Elements with an interactive role and interaction handlers must be focusable. See https://biomejs.dev/linter/rules/use-focusable-interactive

Disallow a missing generic family keyword within font families. See https://biomejs.dev/linter/rules/use-generic-font-names

Enforce that heading elements (h1, h2, etc.) have content and that the content is accessible to screen readers. Accessible means that it is not hidden using the aria-hidden prop. See https://biomejs.dev/linter/rules/use-heading-content

Enforce that html element has lang attribute. See https://biomejs.dev/linter/rules/use-html-lang

Enforces the usage of the attribute title for the element iframe. See https://biomejs.dev/linter/rules/use-iframe-title

Enforce onClick is accompanied by at least one of the following: onKeyUp, onKeyDown, onKeyPress. See https://biomejs.dev/linter/rules/use-key-with-click-events

Enforce onMouseOver / onMouseOut are accompanied by onFocus / onBlur. See https://biomejs.dev/linter/rules/use-key-with-mouse-events

Enforces that audio and video elements must have a track for captions. See https://biomejs.dev/linter/rules/use-media-caption

It detects the use of role attributes in JSX elements and suggests using semantic elements instead. See https://biomejs.dev/linter/rules/use-semantic-elements

Enforce that all anchors are valid, and they are navigable elements. See https://biomejs.dev/linter/rules/use-valid-anchor

Ensures that ARIA properties aria-* are all valid. See https://biomejs.dev/linter/rules/use-valid-aria-props

Elements with ARIA roles must use a valid, non-abstract ARIA role. See https://biomejs.dev/linter/rules/use-valid-aria-role

Enforce that ARIA state and property values are valid. See https://biomejs.dev/linter/rules/use-valid-aria-values

Use valid values for the autocomplete attribute on input elements. See https://biomejs.dev/linter/rules/use-valid-autocomplete

Ensure that the attribute passed to the lang attribute is a correct ISO language and/or country. See https://biomejs.dev/linter/rules/use-valid-lang

It enables the assist actions recommended by Biome. true by default.

Whether Biome should fail in CLI if the assist were not applied to the code.

Whether Biome should enable assist via LSP and CLI.

A list of glob patterns. Biome will include files/folders that will match these patterns.

Disallow unclear usage of consecutive space characters in regular expression literals. See https://biomejs.dev/linter/rules/no-adjacent-spaces-in-regex

Disallow the use of arguments. See https://biomejs.dev/linter/rules/no-arguments

Disallow primitive type aliases and misleading types. See https://biomejs.dev/linter/rules/no-banned-types

Disallow comma operator. See https://biomejs.dev/linter/rules/no-comma-operator

Disallow empty type parameters in type aliases and interfaces. See https://biomejs.dev/linter/rules/no-empty-type-parameters

Disallow functions that exceed a given Cognitive Complexity score. See https://biomejs.dev/linter/rules/no-excessive-cognitive-complexity

Restrict the number of lines of code in a function. See https://biomejs.dev/linter/rules/no-excessive-lines-per-function

This rule enforces a maximum depth to nested describe() in test files. See https://biomejs.dev/linter/rules/no-excessive-nested-test-suites

Disallow unnecessary boolean casts. See https://biomejs.dev/linter/rules/no-extra-boolean-cast

Disallow to use unnecessary callback on flatMap. See https://biomejs.dev/linter/rules/no-flat-map-identity

Prefer for...of statement instead of Array.forEach. See https://biomejs.dev/linter/rules/no-for-each

Disallow shorthand type conversions. See https://biomejs.dev/linter/rules/no-implicit-coercions

Disallow the use of the !important style. See https://biomejs.dev/linter/rules/no-important-styles

This rule reports when a class has no non-static members, such as for a class used exclusively as a static namespace. See https://biomejs.dev/linter/rules/no-static-only-class

Disallow this and super in static contexts. See https://biomejs.dev/linter/rules/no-this-in-static

Disallow unnecessary catch clauses. See https://biomejs.dev/linter/rules/no-useless-catch

Disallow unnecessary constructors. See https://biomejs.dev/linter/rules/no-useless-constructor

Avoid using unnecessary continue. See https://biomejs.dev/linter/rules/no-useless-continue

Disallow empty exports that don't change anything in a module file. See https://biomejs.dev/linter/rules/no-useless-empty-export

Disallow unnecessary escape sequence in regular expression literals. See https://biomejs.dev/linter/rules/no-useless-escape-in-regex

Disallow unnecessary fragments. See https://biomejs.dev/linter/rules/no-useless-fragments

Disallow unnecessary labels. See https://biomejs.dev/linter/rules/no-useless-label

Disallow unnecessary nested block statements. See https://biomejs.dev/linter/rules/no-useless-lone-block-statements

Disallow renaming import, export, and destructured assignments to the same name. See https://biomejs.dev/linter/rules/no-useless-rename

Disallow unnecessary concatenation of string or template literals. See https://biomejs.dev/linter/rules/no-useless-string-concat

Disallow unnecessary String.raw function in template string literals without any escape sequence. See https://biomejs.dev/linter/rules/no-useless-string-raw

Disallow useless case in switch statements. See https://biomejs.dev/linter/rules/no-useless-switch-case

Disallow ternary operators when simpler alternatives exist. See https://biomejs.dev/linter/rules/no-useless-ternary

Disallow useless this aliasing. See https://biomejs.dev/linter/rules/no-useless-this-alias

Disallow using any or unknown as type constraint. See https://biomejs.dev/linter/rules/no-useless-type-constraint

Disallow initializing variables to undefined. See https://biomejs.dev/linter/rules/no-useless-undefined-initialization

Disallow the use of void operators, which is not a familiar operator. See https://biomejs.dev/linter/rules/no-void

Enables the recommended rules for this group

Use arrow functions over function expressions. See https://biomejs.dev/linter/rules/use-arrow-function

Use Date.now() to get the number of milliseconds since the Unix Epoch. See https://biomejs.dev/linter/rules/use-date-now

Promotes the use of .flatMap() when map().flat() are used together. See https://biomejs.dev/linter/rules/use-flat-map

Prefer Array#{indexOf,lastIndexOf}() over Array#{findIndex,findLastIndex}() when looking for the index of an item. See https://biomejs.dev/linter/rules/use-index-of

Enforce the usage of a literal access to properties over computed property access. See https://biomejs.dev/linter/rules/use-literal-keys

Disallow parseInt() and Number.parseInt() in favor of binary, octal, and hexadecimal literals. See https://biomejs.dev/linter/rules/use-numeric-literals

Enforce using concise optional chain instead of chained logical expressions. See https://biomejs.dev/linter/rules/use-optional-chain

Enforce the use of the regular expression literals instead of the RegExp constructor if possible. See https://biomejs.dev/linter/rules/use-regex-literals

Disallow number literal object member names which are not base 10 or use underscore as separator. See https://biomejs.dev/linter/rules/use-simple-number-keys

Discard redundant terms from logical expressions. See https://biomejs.dev/linter/rules/use-simplified-logic-expression

Enforce the use of while loops instead of for loops when the initializer and update expressions are not needed. See https://biomejs.dev/linter/rules/use-while

Regular expression to enforce

Prevent passing of children as props. See https://biomejs.dev/linter/rules/no-children-prop

Prevents from having const variables being re-assigned. See https://biomejs.dev/linter/rules/no-const-assign

Disallow constant expressions in conditions. See https://biomejs.dev/linter/rules/no-constant-condition

Disallow the use of Math.min and Math.max to clamp a value where the result itself is constant. See https://biomejs.dev/linter/rules/no-constant-math-min-max-clamp

Disallow returning a value from a constructor. See https://biomejs.dev/linter/rules/no-constructor-return

Disallow empty character classes in regular expression literals. See https://biomejs.dev/linter/rules/no-empty-character-class-in-regex

Disallows empty destructuring patterns. See https://biomejs.dev/linter/rules/no-empty-pattern

Disallow the use of __dirname and __filename in the global scope. See https://biomejs.dev/linter/rules/no-global-dirname-filename

Disallow calling global object properties as functions. See https://biomejs.dev/linter/rules/no-global-object-calls

Disallow function and var declarations that are accessible outside their block. See https://biomejs.dev/linter/rules/no-inner-declarations

Ensure that builtins are correctly instantiated. See https://biomejs.dev/linter/rules/no-invalid-builtin-instantiation

Prevents the incorrect use of super() inside classes. It also checks whether a call super() is missing from classes that extends other constructors. See https://biomejs.dev/linter/rules/no-invalid-constructor-super

Disallow non-standard direction values for linear gradient functions. See https://biomejs.dev/linter/rules/no-invalid-direction-in-linear-gradient

Disallows invalid named grid areas in CSS Grid Layouts. See https://biomejs.dev/linter/rules/no-invalid-grid-areas

Disallow the use of @import at-rules in invalid positions. See https://biomejs.dev/linter/rules/no-invalid-position-at-import-rule

Disallow the use of variables, function parameters, classes, and enums before their declaration. See https://biomejs.dev/linter/rules/no-invalid-use-before-declaration

Disallow missing var function for css variables. See https://biomejs.dev/linter/rules/no-missing-var-function

Disallows defining React components inside other components. See https://biomejs.dev/linter/rules/no-nested-component-definitions

Forbid the use of Node.js builtin modules. See https://biomejs.dev/linter/rules/no-nodejs-modules

Disallow \8 and \9 escape sequences in string literals. See https://biomejs.dev/linter/rules/no-nonoctal-decimal-escape

Disallow literal numbers that lose precision. See https://biomejs.dev/linter/rules/no-precision-loss

Restrict imports of private exports. See https://biomejs.dev/linter/rules/no-private-imports

Disallow the use of process global. See https://biomejs.dev/linter/rules/no-process-global

Disallow useVisibleTask$() functions in Qwik components. See https://biomejs.dev/linter/rules/no-qwik-use-visible-task

Disallow assigning to React component props. See https://biomejs.dev/linter/rules/no-react-prop-assignments

Prevent the usage of the return value of React.render. See https://biomejs.dev/linter/rules/no-render-return-value

Disallow the use of configured elements. See https://biomejs.dev/linter/rules/no-restricted-elements

Disallow assignments where both sides are exactly the same. See https://biomejs.dev/linter/rules/no-self-assign

Disallow returning a value from a setter. See https://biomejs.dev/linter/rules/no-setter-return

Disallow destructuring props inside JSX components in Solid projects. See https://biomejs.dev/linter/rules/no-solid-destructured-props

Disallow comparison of expressions modifying the string case with non-compliant value. See https://biomejs.dev/linter/rules/no-string-case-mismatch

Disallow lexical declarations in switch clauses. See https://biomejs.dev/linter/rules/no-switch-declarations

Disallow the use of dependencies that aren't specified in the package.json. See https://biomejs.dev/linter/rules/no-undeclared-dependencies

Prevents the usage of variables that haven't been declared inside the document. See https://biomejs.dev/linter/rules/no-undeclared-variables

Disallow unknown CSS value functions. See https://biomejs.dev/linter/rules/no-unknown-function

Disallow unknown media feature names. See https://biomejs.dev/linter/rules/no-unknown-media-feature-name

Disallow unknown properties. See https://biomejs.dev/linter/rules/no-unknown-property

Disallow unknown pseudo-class selectors. See https://biomejs.dev/linter/rules/no-unknown-pseudo-class

Disallow unknown pseudo-element selectors. See https://biomejs.dev/linter/rules/no-unknown-pseudo-element

Disallow unknown type selectors. See https://biomejs.dev/linter/rules/no-unknown-type-selector

Disallow unknown CSS units. See https://biomejs.dev/linter/rules/no-unknown-unit

Disallow unmatchable An+B selectors. See https://biomejs.dev/linter/rules/no-unmatchable-anb-selector

Disallow unreachable code. See https://biomejs.dev/linter/rules/no-unreachable

Ensures the super() constructor is called exactly once on every code path in a class constructor before this is accessed if the class has a superclass. See https://biomejs.dev/linter/rules/no-unreachable-super

Disallow control flow statements in finally blocks. See https://biomejs.dev/linter/rules/no-unsafe-finally

Disallow the use of optional chaining in contexts where the undefined value is not allowed. See https://biomejs.dev/linter/rules/no-unsafe-optional-chaining

Disallow unused function parameters. See https://biomejs.dev/linter/rules/no-unused-function-parameters

Disallow unused imports. See https://biomejs.dev/linter/rules/no-unused-imports

Disallow unused labels. See https://biomejs.dev/linter/rules/no-unused-labels

Disallow unused private class members. See https://biomejs.dev/linter/rules/no-unused-private-class-members

Disallow unused variables. See https://biomejs.dev/linter/rules/no-unused-variables

This rules prevents void elements (AKA self-closing elements) from having children. See https://biomejs.dev/linter/rules/no-void-elements-with-children

Disallow returning a value from a function with the return type 'void'. See https://biomejs.dev/linter/rules/no-void-type-return

Enables the recommended rules for this group

Enforce correct dependency usage within React hooks. See https://biomejs.dev/linter/rules/use-exhaustive-dependencies

Enforce specifying the name of GraphQL operations. See https://biomejs.dev/linter/rules/use-graphql-named-operations

Enforce that all React hooks are being called from the Top Level component functions. See https://biomejs.dev/linter/rules/use-hook-at-top-level

Enforces that <img> elements have both width and height attributes. See https://biomejs.dev/linter/rules/use-image-size

Enforce file extensions for relative imports. See https://biomejs.dev/linter/rules/use-import-extensions

Require calls to isNaN() when checking for NaN. See https://biomejs.dev/linter/rules/use-is-nan

Enforces the use of with { type: "json" } for JSON module imports. See https://biomejs.dev/linter/rules/use-json-import-attributes

Disallow missing key props in iterators/collection literals. See https://biomejs.dev/linter/rules/use-jsx-key-in-iterable

Enforce the consistent use of the radix argument when using parseInt(). See https://biomejs.dev/linter/rules/use-parse-int-radix

Prefer using the class prop as a classlist over the classnames helper. See https://biomejs.dev/linter/rules/use-qwik-classlist

Enforce JSDoc comment lines to start with a single asterisk, except for the first one. See https://biomejs.dev/linter/rules/use-single-js-doc-asterisk

Prevent the usage of static string literal id attribute on elements. See https://biomejs.dev/linter/rules/use-unique-element-ids

Enforce "for" loop update clause moving the counter in the right direction. See https://biomejs.dev/linter/rules/use-valid-for-direction

This rule checks that the result of a typeof expression is compared to a valid value. See https://biomejs.dev/linter/rules/use-valid-typeof

Require generator functions to contain yield. See https://biomejs.dev/linter/rules/use-yield

Control the assist for CSS files.

CSS assist options

CSS formatter options

CSS globals

CSS linter options

CSS parsing options

Control the formatter for CSS (and its super languages) files.

The indent style applied to CSS (and its super languages) files.

The size of the indentation applied to CSS (and its super languages) files. Default to 2.

The type of line ending applied to CSS (and its super languages) files. auto uses CRLF on Windows and LF on other platforms.

What's the max width of a line applied to CSS (and its super languages) files. Defaults to 80.

The type of quotes used in CSS code. Defaults to double.

Control the linter for CSS files.

Allow comments to appear on incorrect lines in .css files

Enables parsing of CSS Modules specific features.

Enables parsing of Tailwind CSS 4.0 directives and functions.

Deprecated: Please use force-ignore syntax in files.includes instead: https://biomejs.dev/reference/configuration/#filesincludes

Set of file and folder names that should be unconditionally ignored by Biome's scanner.

Tells Biome to not emit diagnostics when handling files that it doesn't know

A list of glob patterns. Biome will handle only those files/folders that will match these patterns.

The maximum allowed size for source code files in bytes. Files above this limit will be ignored for performance reasons. Defaults to 1 MiB

The attribute position style in HTML-ish languages. Defaults to auto.

Put the > of a multi-line HTML or JSX element at the end of the last line instead of being alone on the next line (does not apply to self closing elements).

Whether to insert spaces around brackets in object literals. Defaults to true.

Whether to expand arrays and objects on multiple lines. When set to auto, object literals are formatted on multiple lines if the first property has a newline, and array literals are formatted on a single line if it fits in the line. When set to always, these literals are formatted on multiple lines, regardless of length of the list. When set to never, these literals are formatted on a single line if it fits in the line. When formatting package.json, Biome will use always unless configured otherwise. Defaults to "auto".

Whether formatting should be allowed to proceed if a given file has syntax errors

A list of glob patterns. The formatter will include files/folders that will match these patterns.

The indent style.

The size of the indentation, 2 by default

The type of line ending.

What's the max width of a line. Defaults to 80.

Use any .editorconfig files to configure the formatter. Configuration in biome.json will override .editorconfig configuration.

Default: true.

Control the formatter for GraphQL files.

Assist options

GraphQL formatter options

Whether to insert spaces around brackets in object literals. Defaults to true.

Control the formatter for GraphQL files.

The indent style applied to GraphQL files.

The size of the indentation applied to GraphQL files. Default to 2.

The type of line ending applied to GraphQL files. auto uses CRLF on Windows and LF on other platforms.

What's the max width of a line applied to GraphQL files. Defaults to 80.

The type of quotes used in GraphQL code. Defaults to double.

Control the formatter for GraphQL files.

Control the assist functionality for Grit files.

Assist options

Formatting options

Formatting options

Control the formatter for Grit files.

The indent style applied to Grit files.

The size of the indentation applied to Grit files. Default to 2.

The type of line ending applied to Grit files.

What's the max width of a line applied to Grit files. Defaults to 80.

Control the linter for Grit files.

The "position" of the closure function, starting from zero.

For example, for React's useEffect() hook, the closure index is 0.

The "position" of the array of dependencies, starting from zero.

For example, for React's useEffect() hook, the dependencies index is 1.

The name of the hook.

Whether the result of the hook is stable.

Set to true to mark the identity of the hook's return value as stable, or use a number/an array of numbers to mark the "positions" in the return array as stable.

For example, for React's useRef() hook the value would be true, while for useState() it would be [1].

Control the assist for HTML (and its super languages) files.

Enables full support for HTML, Vue, Svelte and Astro files.

HTML formatter options

HTML linter options

HTML parsing options

The attribute position style in HTML elements. Defaults to auto.

Whether to hug the closing bracket of multiline HTML tags to the end of the last line, rather than being alone on the following line. Defaults to false.

Control the formatter for HTML (and its super languages) files.

Whether to indent the <script> and <style> tags for HTML (and its super languages). Defaults to false.

The indent style applied to HTML (and its super languages) files.

The size of the indentation applied to HTML (and its super languages) files. Default to 2.

The type of line ending applied to HTML (and its super languages) files. auto uses CRLF on Windows and LF on other platforms.

What's the max width of a line applied to HTML (and its super languages) files. Defaults to 80.

Whether void elements should be self-closed. Defaults to never.

Whether to account for whitespace sensitivity when formatting HTML (and its super languages). Defaults to "css".

Control the linter for HTML (and its super languages) files.

Enables the parsing of double text expressions such as {{ expression }} inside .html files

Control the assist for JavaScript (and its super languages) files.

Assist options

Formatting options

A list of global bindings that should be ignored by the analyzers

If defined here, they should not emit diagnostics.

Indicates the type of runtime or transformation used for interpreting JSX.

Linter options

Parsing options

Whether to add non-necessary parentheses to arrow functions. Defaults to "always".

The attribute position style in JSX elements. Defaults to auto.

Whether to hug the closing bracket of multiline HTML/JSX tags to the end of the last line, rather than being alone on the following line. Defaults to false.

Whether to insert spaces around brackets in object literals. Defaults to true.

Control the formatter for JavaScript (and its super languages) files.

Whether to expand arrays and objects on multiple lines. When set to auto, object literals are formatted on multiple lines if the first property has a newline, and array literals are formatted on a single line if it fits in the line. When set to always, these literals are formatted on multiple lines, regardless of length of the list. When set to never, these literals are formatted on a single line if it fits in the line. When formatting package.json, Biome will use always unless configured otherwise. Defaults to "auto".

The indent style applied to JavaScript (and its super languages) files.

The size of the indentation applied to JavaScript (and its super languages) files. Default to 2.

The type of quotes used in JSX. Defaults to double.

The type of line ending applied to JavaScript (and its super languages) files. auto uses CRLF on Windows and LF on other platforms.

What's the max width of a line applied to JavaScript (and its super languages) files. Defaults to 80.

When breaking binary expressions into multiple lines, whether to break them before or after the binary operator. Defaults to "after".

When properties in objects are quoted. Defaults to asNeeded.

The type of quotes used in JavaScript code. Defaults to double.

Whether the formatter prints semicolons for all statements or only in for statements where it is necessary because of ASI.

Print trailing commas wherever possible in multi-line comma-separated syntactic structures. Defaults to "all".

Control the linter for JavaScript (and its super languages) files.

Enables parsing of Grit metavariables. Defaults to false.

When enabled, files like .js/.mjs/.cjs may contain JSX syntax.

Defaults to true.

It enables the experimental and unsafe parsing of parameter decorators

These decorators belong to an old proposal, and they are subject to change.

Control the assist for JSON (and its super languages) files.

Assist options

Formatting options

Linting options

Parsing options

Whether to insert spaces around brackets in object literals. Defaults to true.

Control the formatter for JSON (and its super languages) files.

Whether to expand arrays and objects on multiple lines. When set to auto, object literals are formatted on multiple lines if the first property has a newline, and array literals are formatted on a single line if it fits in the line. When set to always, these literals are formatted on multiple lines, regardless of length of the list. When set to never, these literals are formatted on a single line if it fits in the line. When formatting package.json, Biome will use always unless configured otherwise. Defaults to "auto".

The indent style applied to JSON (and its super languages) files.

The size of the indentation applied to JSON (and its super languages) files. Default to 2.

The type of line ending applied to JSON (and its super languages) files. auto uses CRLF on Windows and LF on other platforms.

What's the max width of a line applied to JSON (and its super languages) files. Defaults to 80.

Print trailing commas wherever possible in multi-line comma-separated syntactic structures. Defaults to "none".

Control the linter for JSON (and its super languages) files.

Allow parsing comments in .json files

Allow parsing trailing commas in .json files

An object where the keys are the names of the domains, and the values are all, recommended, or none.

if false, it disables the feature and the linter won't be executed. true by default

A list of glob patterns. The analyzer will handle only those files/folders that will match these patterns.

List of rules

It allows users to modify the strings that can be checked for in the anchor text. Useful for specifying other words in other languages

Allows a list of bitwise operators to be used as exceptions.

List of domains where target="_blank" is allowed without rel="noopener".

Whether noreferrer is allowed in addition to noopener.

A list of (non-confusing) labels that should be allowed

Allowed calls on the console object.

If true, an exception is made when comparing with null, as it's often relied on to check both for null or undefined.

If false, no such exception will be made.

Whether comments are considered meaningful

The maximum complexity score that we allow. Anything higher is considered excessive.

The maximum number of lines allowed in a function body.

When this options is set to true, blank lines in the function body are not counted towards the maximum line limit.

When this option is set to true, Immediately Invoked Function Expressions (IIFEs) are not checked for the maximum line limit.

A list of variable names allowed for forEach calls.

Ignores type-only imports when finding an import cycle. A type-only import (import type) will be removed by the compiler, so it cuts an import cycle at runtime. Note that named type imports (import { type Foo }) aren't considered as type-only because it's not removed by the compiler if the verbatimModuleSyntax option is enabled. Enabled by default.

Allows unary operators ++ and -- in the afterthought (final expression) of a for loop.

An array of strings that won't trigger the rule. Whitespaces are taken into consideration

When enabled, strings inside props are always ignored

When enabled, also flag string literals inside JSX expressions and attributes

Array of component names that should be considered the same as an input element.

Array of attributes that should be treated as the label accessible text content.

Array of component names that should be considered the same as a label element.

Whether to report an error when a dependency is listed in the dependencies array but isn't used. Defaults to allow.

The default visibility to assume for symbols without visibility tag.

Default: public.

A list of additional JSON files that should be checked.

Elements to restrict. Each key is the element name, and the value is the message to show when the element is used.

A list of names that should trigger the rule

A list of import paths that should trigger the rule.

gitignore-style patterns that should trigger the rule.

Set entropy threshold (default is 41).

If set to false, then the rule will show an error when devDependencies are imported. Defaults to true.

If set to false, then the rule will show an error when optionalDependencies are imported. Defaults to true.

If set to false, then the rule will show an error when peerDependencies are imported. Defaults to true.

Environment variables that should always be allowed. Use this to specify environment variables that are always available in your environment, even when not declared in turbo.json. Supports regular expressions, e.g. ["MY_ENV_.*"].

Check undeclared types.

A list of unknown at-rule names to ignore (case-insensitive).

Whether to ignore unused variables from an object destructuring with a spread.

Whether to ignore unused variables from an object destructuring with a spread.

Disallow ambiguous anchor descriptions. See https://biomejs.dev/linter/rules/no-ambiguous-anchor-text

Prevent usage of next/script's beforeInteractive strategy outside of pages/_document.js in a Next.js project. See https://biomejs.dev/linter/rules/no-before-interactive-script-outside-document

Disallow continue statements. See https://biomejs.dev/linter/rules/no-continue

Restrict imports of deprecated exports. See https://biomejs.dev/linter/rules/no-deprecated-imports

Prevent the listing of duplicate dependencies. The rule supports the following dependency groups: "bundledDependencies", "bundleDependencies", "dependencies", "devDependencies", "overrides", "optionalDependencies", and "peerDependencies". See https://biomejs.dev/linter/rules/no-duplicate-dependencies

Disallow JSX prop spreading the same identifier multiple times. See https://biomejs.dev/linter/rules/no-duplicated-spread-props

Disallow empty sources. See https://biomejs.dev/linter/rules/no-empty-source

Require the use of === or !== for comparison with null. See https://biomejs.dev/linter/rules/no-equals-to-null

Require Promise-like statements to be handled appropriately. See https://biomejs.dev/linter/rules/no-floating-promises

Disallow iterating using a for-in loop. See https://biomejs.dev/linter/rules/no-for-in

Prevent import cycles. See https://biomejs.dev/linter/rules/no-import-cycles

Disallows the usage of the unary operators ++ and --. See https://biomejs.dev/linter/rules/no-increment-decrement

Disallow string literals inside JSX elements. See https://biomejs.dev/linter/rules/no-jsx-literals

Disallow .bind(), arrow functions, or function expressions in JSX props. See https://biomejs.dev/linter/rules/no-jsx-props-bind

Prevent problematic leaked values from being rendered. See https://biomejs.dev/linter/rules/no-leaked-render

Disallow Promises to be used in places where they are almost certainly a mistake. See https://biomejs.dev/linter/rules/no-misused-promises

Disallow use of chained assignment expressions. See https://biomejs.dev/linter/rules/no-multi-assign

Disallow creating multiline strings by escaping newlines. See https://biomejs.dev/linter/rules/no-multi-str

Prevent client components from being async functions. See https://biomejs.dev/linter/rules/no-next-async-client-component

Disallow function parameters that are only used in recursive calls. See https://biomejs.dev/linter/rules/no-parameters-only-used-in-recursion

Disallow the use of the deprecated proto object property. See https://biomejs.dev/linter/rules/no-proto

Replaces usages of forwardRef with passing ref as a prop. See https://biomejs.dev/linter/rules/no-react-forward-ref

Disallow assignments in return statements. See https://biomejs.dev/linter/rules/no-return-assign

Disallow javascript: URLs in HTML. See https://biomejs.dev/linter/rules/no-script-url

Disallow variable declarations from shadowing variables declared in the outer scope. See https://biomejs.dev/linter/rules/no-shadow

Prevent the usage of synchronous scripts. See https://biomejs.dev/linter/rules/no-sync-scripts

Disallow ternary operators. See https://biomejs.dev/linter/rules/no-ternary

Disallow the use of undeclared environment variables. See https://biomejs.dev/linter/rules/no-undeclared-env-vars

Disallow unknown DOM properties. See https://biomejs.dev/linter/rules/no-unknown-attribute

Disallow unnecessary type-based conditions that can be statically determined as redundant. See https://biomejs.dev/linter/rules/no-unnecessary-conditions

Warn when importing non-existing exports. See https://biomejs.dev/linter/rules/no-unresolved-imports

Disallow expression statements that are neither a function call nor an assignment. See https://biomejs.dev/linter/rules/no-unused-expressions

Disallow unused catch bindings. See https://biomejs.dev/linter/rules/no-useless-catch-binding

Disallow the use of useless undefined. See https://biomejs.dev/linter/rules/no-useless-undefined

Enforce that Vue component data options are declared as functions. See https://biomejs.dev/linter/rules/no-vue-data-object-declaration

Disallow duplicate keys in Vue component data, methods, computed properties, and other options. See https://biomejs.dev/linter/rules/no-vue-duplicate-keys

Disallow reserved keys in Vue component data and computed properties. See https://biomejs.dev/linter/rules/no-vue-reserved-keys

Disallow reserved names to be used as props. See https://biomejs.dev/linter/rules/no-vue-reserved-props

Disallow destructuring of props passed to setup in Vue projects. See https://biomejs.dev/linter/rules/no-vue-setup-props-reactivity-loss

Disallow using v-if and v-for directives on the same element. See https://biomejs.dev/linter/rules/no-vue-v-if-with-v-for

Enables the recommended rules for this group

Require Array#sort and Array#toSorted calls to always provide a compareFunction. See https://biomejs.dev/linter/rules/use-array-sort-compare

Enforce that await is only used on Promise values. See https://biomejs.dev/linter/rules/use-await-thenable

Enforce consistent arrow function bodies. See https://biomejs.dev/linter/rules/use-consistent-arrow-return

Require all descriptions to follow the same style (either block or inline) to maintain consistency and improve readability across the schema. See https://biomejs.dev/linter/rules/use-consistent-graphql-descriptions

Require the @deprecated directive to specify a deletion date. See https://biomejs.dev/linter/rules/use-deprecated-date

Require destructuring from arrays and/or objects. See https://biomejs.dev/linter/rules/use-destructuring

Require switch-case statements to be exhaustive. See https://biomejs.dev/linter/rules/use-exhaustive-switch-cases

Enforce types in functions, methods, variables, and parameters. See https://biomejs.dev/linter/rules/use-explicit-type

Enforce the use of Array.prototype.find() over Array.prototype.filter() followed by [0] when looking for a single result. See https://biomejs.dev/linter/rules/use-find

Enforce a maximum number of parameters in function definitions. See https://biomejs.dev/linter/rules/use-max-params

Disallow use* hooks outside of component$ or other use* hooks in Qwik applications. See https://biomejs.dev/linter/rules/use-qwik-method-usage

Disallow unserializable expressions in Qwik dollar ($) scopes. See https://biomejs.dev/linter/rules/use-qwik-valid-lexical-scope

Enforce RegExp#exec over String#match if no global flag is provided. See https://biomejs.dev/linter/rules/use-regexp-exec

Enforce the presence of required scripts in package.json. See https://biomejs.dev/linter/rules/use-required-scripts

Enforce the sorting of CSS utility classes. See https://biomejs.dev/linter/rules/use-sorted-classes

Enforce the use of the spread operator over .apply(). See https://biomejs.dev/linter/rules/use-spread

Require all argument names for fields & directives to be unique. See https://biomejs.dev/linter/rules/use-unique-argument-names

Require all fields of a type to be unique. See https://biomejs.dev/linter/rules/use-unique-field-definition-names

Enforce unique operation names across a GraphQL document. See https://biomejs.dev/linter/rules/use-unique-graphql-operation-name

Require fields within an input object to be unique. See https://biomejs.dev/linter/rules/use-unique-input-field-names

Require all variable definitions to be unique. See https://biomejs.dev/linter/rules/use-unique-variable-names

Enforce consistent defineProps declaration style. See https://biomejs.dev/linter/rules/use-vue-consistent-define-props-declaration

Enforce a consistent style for v-bind in Vue templates. See https://biomejs.dev/linter/rules/use-vue-consistent-v-bind-style

Enforce a consistent style for v-on in Vue templates. See https://biomejs.dev/linter/rules/use-vue-consistent-v-on-style

Enforce specific order of Vue compiler macros. See https://biomejs.dev/linter/rules/use-vue-define-macros-order

Enforce hyphenated (kebab-case) attribute names in Vue templates. See https://biomejs.dev/linter/rules/use-vue-hyphenated-attributes

Enforce multi-word component names in Vue components. See https://biomejs.dev/linter/rules/use-vue-multi-word-component-names

Enforce that elements using v-for also specify a unique key. See https://biomejs.dev/linter/rules/use-vue-v-for-key

Enforce valid Vue <template> root usage. See https://biomejs.dev/linter/rules/use-vue-valid-template-root

Forbids v-bind directives with missing arguments or invalid modifiers. See https://biomejs.dev/linter/rules/use-vue-valid-v-bind

Enforce valid v-cloak Vue directives. See https://biomejs.dev/linter/rules/use-vue-valid-v-cloak

Enforce valid usage of v-else. See https://biomejs.dev/linter/rules/use-vue-valid-v-else

Enforce valid v-else-if directives. See https://biomejs.dev/linter/rules/use-vue-valid-v-else-if

Enforce valid v-html directives. See https://biomejs.dev/linter/rules/use-vue-valid-v-html

Enforces valid v-if usage for Vue templates. See https://biomejs.dev/linter/rules/use-vue-valid-v-if

Enforce valid v-on directives with proper arguments, modifiers, and handlers. See https://biomejs.dev/linter/rules/use-vue-valid-v-on

Enforce valid v-once Vue directives. See https://biomejs.dev/linter/rules/use-vue-valid-v-once

Enforce valid v-pre Vue directives. See https://biomejs.dev/linter/rules/use-vue-valid-v-pre

Enforce valid v-text Vue directives. See https://biomejs.dev/linter/rules/use-vue-valid-v-text

Enforce opting in to Vue Vapor mode in <script setup> blocks. See https://biomejs.dev/linter/rules/use-vue-vapor

List of actions

if false, it disables the feature and the assist won't be executed. true by default

File size limit in bytes

The attribute position style.

Put the > of a multi-line HTML or JSX element at the end of the last line instead of being alone on the next line (does not apply to self closing elements).

Whether to insert spaces around brackets in object literals. Defaults to true.

Whether to expand arrays and objects on multiple lines. When set to auto, object literals are formatted on multiple lines if the first property has a newline, and array literals are formatted on a single line if it fits in the line. When set to always, these literals are formatted on multiple lines, regardless of length of the list. When set to never, these literals are formatted on a single line if it fits in the line. When formatting package.json, Biome will use always unless configured otherwise. Defaults to "auto".

Stores whether formatting should be allowed to proceed if a given file has syntax errors

The size of the indentation, 2 by default (deprecated, use indent-width)

The indent style.

The size of the indentation, 2 by default

The type of line ending.

What's the max width of a line. Defaults to 80.

List of rules

if false, it disables the feature and the linter won't be executed. true by default

List of rules

Specific configuration for the Json language

Specific configuration for the CSS language

Specific configuration for the filesystem

Specific configuration for the Json language

Specific configuration for the Graphql language

Specific configuration for the GritQL language

Specific configuration for the GritQL language

A list of glob patterns. Biome will include files/folders that will match these patterns.

Specific configuration for the JavaScript language

Specific configuration for the Json language

Specific configuration for the Json language

Specific configuration for additional plugins

Names of the exported members that allowed to be not be used.

Names of the exported members that should not be used.

The message to display when this module is imported.

An array of gitignore-style patterns.

A regex pattern for import names to forbid within the matched modules.

If true, the matched patterns in the importNamePattern will be allowed. Defaults to false.

A custom message for diagnostics related to this pattern.

Disallow the use of spread (...) syntax on accumulators. See https://biomejs.dev/linter/rules/no-accumulating-spread

Disallow await inside loops. See https://biomejs.dev/linter/rules/no-await-in-loops

Disallow the use of barrel file. See https://biomejs.dev/linter/rules/no-barrel-file

Disallow the use of the delete operator. See https://biomejs.dev/linter/rules/no-delete

Disallow accessing namespace imports dynamically. See https://biomejs.dev/linter/rules/no-dynamic-namespace-import-access

Prevent usage of <img> element in a Next.js project. See https://biomejs.dev/linter/rules/no-img-element

Disallow the use of namespace imports. See https://biomejs.dev/linter/rules/no-namespace-import

Avoid re-export all. See https://biomejs.dev/linter/rules/no-re-export-all

Prevent duplicate polyfills from Polyfill.io. See https://biomejs.dev/linter/rules/no-unwanted-polyfillio

Enables the recommended rules for this group

Ensure the preconnect attribute is used when using Google Fonts. See https://biomejs.dev/linter/rules/use-google-font-preconnect

Enforce using Solid's <For /> component for mapping an array to JSX elements. See https://biomejs.dev/linter/rules/use-solid-for-component

Require regex literals to be declared at the top level. See https://biomejs.dev/linter/rules/use-top-level-regex