Configuration
2.0.4Schema URL
The configuration that is contained inside the file biome.json
Properties
A field for the JSON schema specification
Specific configuration for assists
Specific configuration for the Css language
A list of paths to other JSON files, used to extends the current configuration.
The configuration of the filesystem
The configuration of the formatter
Specific configuration for the GraphQL language
Specific configuration for the GraphQL language
Specific configuration for the HTML language
Specific configuration for the JavaScript language
Specific configuration for the Json language
The configuration for the linter
A list of granular patterns that should be applied only to a sub set of files
List of plugins to load.
Indicates whether this configuration file is at the root of a Biome project. By default, this is true.
The configuration of the VCS integration
Definitions
A list of rules that belong to this group
Enforce that the accessKey attribute is not used on any HTML element.
Enforce that aria-hidden="true" is not set on focusable elements.
Enforce that elements that do not support ARIA roles, states, and properties do not have those attributes.
Enforce that autoFocus prop is not used on elements.
Enforces that no distracting elements are used.
The scope prop should be used only on <th> elements.
Enforce that non-interactive ARIA roles are not assigned to interactive HTML elements.
Enforce that a label element or component has a text label and an associated input.
Enforce that interactive ARIA roles are not assigned to non-interactive HTML elements.
Enforce that tabIndex is not assigned to non-interactive HTML elements.
Prevent the usage of positive integers on tabIndex property
Enforce img alt prop does not contain the word "image", "picture", or "photo".
Enforce explicit role property is not the same as implicit/default role property on an element.
Enforce that static, visible elements (such as <div>) that have click handlers use the valid role attribute.
Enforces the usage of the title element for the svg element.
It 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.
Enforce that anchors have content and that the content is accessible to screen readers.
Enforce that tabIndex is assigned to non-interactive HTML elements with aria-activedescendant.
Enforce that elements with ARIA roles must have all required ARIA attributes for that role.
Enforce that ARIA properties are valid for the roles that are supported by the element.
Enforces the usage of the attribute type for the element button
Elements with an interactive role and interaction handlers must be focusable.
Disallow a missing generic family keyword within font families.
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.
Enforce that html element has lang attribute.
Enforces the usage of the attribute title for the element iframe.
Enforce onClick is accompanied by at least one of the following: onKeyUp, onKeyDown, onKeyPress.
Enforce onMouseOver / onMouseOut are accompanied by onFocus / onBlur.
Enforces that audio and video elements must have a track for captions.
It detects the use of role attributes in JSX elements and suggests using semantic elements instead.
Enforce that all anchors are valid, and they are navigable elements.
Ensures that ARIA properties aria-* are all valid.
Elements with ARIA roles must use a valid, non-abstract ARIA role.
Enforce that ARIA state and property values are valid.
Use valid values for the autocomplete attribute on input elements.
Ensure that the attribute passed to the lang attribute is a correct ISO language and/or country.
It enables the assist actions recommended by Biome. true by default.
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).
A list of rules that belong to this group
Disallow unclear usage of consecutive space characters in regular expression literals
Disallow the use of arguments.
Disallow primitive type aliases and misleading types.
Disallow comma operator.
Disallow empty type parameters in type aliases and interfaces.
Disallow functions that exceed a given Cognitive Complexity score.
This rule enforces a maximum depth to nested describe() in test files.
Disallow unnecessary boolean casts
Disallow to use unnecessary callback on flatMap.
Prefer for...of statement instead of Array.forEach.
This rule reports when a class has no non-static members, such as for a class used exclusively as a static namespace.
Disallow this and super in static contexts.
Disallow unnecessary catch clauses.
Disallow unnecessary constructors.
Avoid using unnecessary continue.
Disallow empty exports that don't change anything in a module file.
Disallow unnecessary escape sequence in regular expression literals.
Disallow unnecessary fragments
Disallow unnecessary labels.
Disallow unnecessary nested block statements.
Disallow renaming import, export, and destructured assignments to the same name.
Disallow unnecessary concatenation of string or template literals.
Disallow unnecessary String.raw function in template string literals without any escape sequence.
Disallow useless case in switch statements.
Disallow ternary operators when simpler alternatives exist.
Disallow useless this aliasing.
Disallow using any or unknown as type constraint.
Disallow initializing variables to undefined.
Disallow the use of void operators, which is not a familiar operator.
It enables the recommended rules for this group
Use arrow functions over function expressions.
Use Date.now() to get the number of milliseconds since the Unix Epoch.
Promotes the use of .flatMap() when map().flat() are used together.
Enforce the usage of a literal access to properties over computed property access.
Disallow parseInt() and Number.parseInt() in favor of binary, octal, and hexadecimal literals
Enforce using concise optional chain instead of chained logical expressions.
Enforce the use of the regular expression literals instead of the RegExp constructor if possible.
Disallow number literal object member names which are not base 10 or use underscore as separator.
Discard redundant terms from logical expressions.
Enforce the use of while loops instead of for loops when the initializer and update expressions are not needed.
Options for the rule noExcessiveCognitiveComplexity.
The maximum complexity score that we allow. Anything higher is considered excessive.
A list of rules that belong to this group
Prevent passing of children as props.
Prevents from having const variables being re-assigned.
Disallow constant expressions in conditions
Disallow the use of Math.min and Math.max to clamp a value where the result itself is constant.
Disallow returning a value from a constructor.
Disallow empty character classes in regular expression literals.
Disallows empty destructuring patterns.
Disallow calling global object properties as functions
Disallow function and var declarations that are accessible outside their block.
Ensure that builtins are correctly instantiated.
Prevents the incorrect use of super() inside classes. It also checks whether a call super() is missing from classes that extends other constructors.
Disallow non-standard direction values for linear gradient functions.
Disallows invalid named grid areas in CSS Grid Layouts.
Disallow the use of @import at-rules in invalid positions.
Disallow the use of variables and function parameters before their declaration
Disallow missing var function for css variables.
Forbid the use of Node.js builtin modules.
Disallow \8 and \9 escape sequences in string literals.
Disallow literal numbers that lose precision
Restrict imports of private exports.
Prevent the usage of the return value of React.render.
Disallow assignments where both sides are exactly the same.
Disallow returning a value from a setter
Disallow comparison of expressions modifying the string case with non-compliant value.
Disallow lexical declarations in switch clauses.
Disallow the use of dependencies that aren't specified in the package.json.
Prevents the usage of variables that haven't been declared inside the document.
Disallow unknown CSS value functions.
Disallow unknown media feature names.
Disallow unknown properties.
Disallow unknown pseudo-class selectors.
Disallow unknown pseudo-element selectors.
Disallow unknown type selectors.
Disallow unknown CSS units.
Disallow unmatchable An+B selectors.
Disallow unreachable code
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
Disallow control flow statements in finally blocks.
Disallow the use of optional chaining in contexts where the undefined value is not allowed.
Disallow unused function parameters.
Disallow unused imports.
Disallow unused labels.
Disallow unused private class members
Disallow unused variables.
This rules prevents void elements (AKA self-closing elements) from having children.
Disallow returning a value from a function with the return type 'void'
It enables the recommended rules for this group
Enforce all dependencies are correctly specified in a React hook.
Enforce that all React hooks are being called from the Top Level component functions.
Enforce file extensions for relative imports.
Require calls to isNaN() when checking for NaN.
Disallow missing key props in iterators/collection literals.
Enforce "for" loop update clause moving the counter in the right direction.
This rule checks that the result of a typeof expression is compared to a valid value.
Require generator functions to contain yield.
Options that changes how the CSS assist behaves
Control the assist for CSS files.
Options applied to CSS files
CSS assist options
CSS formatter options
CSS globals
CSS linter options
CSS parsing options
Options that changes how the CSS formatter behaves
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.
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.
Options that changes how the CSS linter behaves
Control the linter for CSS files.
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.
Options for the useHookAtTopLevel rule have been deprecated, since we now use the React hook naming convention to determine whether a function is a hook.
Supported cases for file names.
Rule's options.
Regular expression to enforce
If false, then non-ASCII characters are allowed.
If false, then consecutive uppercase are allowed in camel and pascal cases. This does not affect other [Case].
The configuration of the filesystem
Set of file and folder names that should be unconditionally ignored by Biome's scanner.
Biome maintains an internal list of default ignore entries, which is based on user feedback and which may change in any release. This setting allows overriding this internal list completely.
This is considered an advanced feature that users should not need to tweak themselves, but they can as a last resort. This setting can only be configured in root configurations, and is ignored in nested configs.
Entries must be file or folder names. Specific paths and globs are not supported.
Examples where this may be useful:
```jsonc { "files": { "experimentalScannerIgnores": [ // You almost certainly don't want to scan your .git // folder, which is why it's already ignored by default: ".git",
// But the scanner does scan node_modules by default. If // you really don't want this, you can ignore it like // this: "node_modules",
// But it's probably better to ignore a specific dependency. // For instance, one that happens to be particularly slow to // scan: "RedisCommander.d.ts", ], } } ```
Please be aware that rules relying on the module graph or type inference information may be negatively affected if dependencies of your project aren't (fully) scanned.
Tells Biome to not emit diagnostics when handling files that 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
Used to identify the kind of code action emitted by a rule
Supported cases.
Generic options applied to all files
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".
Stores 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.
Options that changes how the GraphQL linter behaves
Control the formatter for GraphQL files.
Options applied to GraphQL files
Assist options
GraphQL formatter options
Options that changes how the GraphQL formatter behaves
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.
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.
Options that change how the GraphQL linter behaves.
Control the formatter for GraphQL files.
Control the assist functionality for Grit files.
Options applied to GritQL 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].
Options applied to HTML files
HTML formatter options
HTML parsing options
Options that changes how the HTML formatter behaves
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.
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".
Options that changes how the HTML parser behaves
Glob to match against import sources.
Rule's options.
Rule's options.
Whether to indent the content of <script> and <style> tags for HTML-ish templating languages (Vue, Svelte, etc.).
When true, the content of <script> and <style> tags will be indented one level.
Assist options specific to the JavaScript assist
Control the assist for JavaScript (and its super languages) files.
A set of options applied to the JavaScript 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
Formatting options specific to the JavaScript files
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.
What's the max width of a line applied to JavaScript (and its super languages) files. Defaults to 80.
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".
Linter options specific to the JavaScript linter
Control the linter for JavaScript (and its super languages) files.
Options that changes how the JavaScript parser behaves
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.
Linter options specific to the JSON linter
Control the assist for JSON (and its super languages) files.
Options applied to JSON 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.
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".
Linter options specific to the JSON linter
Control the linter for JSON (and its super languages) files.
Indicates the type of runtime or transformation used for interpreting JSX.
Validated value for the line_width formatter options
The allowed range of values is 1..=320
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
Rule's options.
Custom conventions.
If false, then non-ASCII characters are allowed.
If false, then consecutive uppercase are allowed in camel and pascal cases. This does not affect other [Case].
Rule's options
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.
Options for the rule noConfusingLabels
A list of (non-confusing) labels that should be allowed
Allowed calls on the console object.
Rule's options
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.
A list of variable names allowed for forEach calls.
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.
[]Options for the rule NoParameterAssign
Whether to report an error when a dependency is listed in the dependencies array but isn't used. Defaults to allow.
Options for the rule noPrivateImports.
The default visibility to assume for symbols without visibility tag.
Default: public.
Elements to restrict. Each key is the element name, and the value is the message to show when the element is used.
{}Set entropy threshold (default is 41).
Rule's options
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.
Whether to ignore unused variables from an object destructuring with a spread.
Normalized Biome glob pattern that strips ./ from the pattern.
A list of rules that belong to this group
Disallow await inside loops.
Disallow bitwise operators.
Disallow expressions where the operation doesn't affect the value
Disallow destructuring props inside JSX components in Solid projects.
Require Promise-like statements to be handled appropriately.
Disallow the use of __dirname and __filename in the global scope.
Prevent import cycles.
Disallow the use of the !important style.
Disallows defining React components inside other components.
Disallow use event handlers on non-interactive elements.
Disallow the use of process global.
Disallow assigning to React component props.
Disallow the use of configured elements.
Disallow usage of sensitive data such as API keys and tokens.
Disallow variable declarations from shadowing variables declared in the outer scope.
Prevents the use of the TypeScript directive @ts-ignore.
Disallow unknown at-rules.
Warn when importing non-existing exports.
Prevent duplicate polyfills from Polyfill.io.
Disallow useless backreferences in regular expression literals that always match an empty string.
Disallow unnecessary escapes in string literals.
Disallow the use of useless undefined.
It enables the recommended rules for this group
Enforce that getters and setters for the same property are adjacent in class and object definitions.
Require the consistent declaration of object literals. Defaults to explicit definitions.
Use static Response methods instead of new Response() constructor when possible.
Require switch-case statements to be exhaustive.
Enforce types in functions, methods, variables, and parameters.
Require that all exports are declared after all non-export statements.
Enforce using Solid's <For /> component for mapping an array to JSX elements.
Ensure the preconnect attribute is used when using Google Fonts.
Prefer Array#{indexOf,lastIndexOf}() over Array#{findIndex,findLastIndex}() when looking for the index of an item.
Enforce consistent return values in iterable callbacks.
Enforces the use of with { type: "json" } for JSON module imports.
Enforce specifying the name of GraphQL operations.
Validates that all enum values are capitalized.
Enforce the use of numeric separators in numeric literals.
Prefer object spread over Object.assign() when constructing new objects.
Enforce the consistent use of the radix argument when using parseInt().
Enforce marking members as readonly if they are never modified outside the constructor.
Enforce JSDoc comment lines to start with a single asterisk, except for the first one.
Enforce the sorting of CSS utility classes.
Require a description parameter for the Symbol().
Prevent the usage of static string literal id attribute on elements.
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
A list of rules that belong to this group
Disallow the use of spread (...) syntax on accumulators.
Disallow the use of barrel file.
Disallow the use of the delete operator.
Disallow accessing namespace imports dynamically.
Prevent usage of <img> element in a Next.js project.
Disallow the use of namespace imports.
Avoid re-export all.
It enables the recommended rules for this group
Require regex literals to be declared at the top level.
Specifies whether property assignments on function parameters are allowed or denied.
Rule's options
When true, the keywords public, protected, and private are analyzed by the rule.
Options for the rule noRestrictedGlobals.
A list of names that should trigger the rule
Options for the rule noRestrictedImports.
A list of import paths that should trigger the rule.
The severity of the emitted diagnostics by the rule
Rule's options
The severity of the emitted diagnostics by the rule
Rule domains
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
The severity of the emitted diagnostics by the rule
The kind of the code actions emitted by the rule
It enables the lint rules recommended by Biome. true by default.
A list of rules that belong to this group
Disallow target="_blank" attribute without rel="noopener".
Prevent the usage of dangerous JSX props
Report when a DOM element or a component uses both children and dangerouslySetInnerHTML prop.
Disallow the use of global eval().
It enables the recommended rules for this group
Controls whether void-elements should be self closed
A list of rules that belong to this group
Provides a code action to sort the imports and exports in the file using a built-in or custom order.
It enables the recommended rules for this group
Enforce attribute sorting in JSX elements.
Sorts the keys of a JSON object in natural order
Enforce ordering of CSS properties and nested rules.
A list of rules that belong to this group
Disallow use of CommonJs module system in favor of ESM style imports.
Disallow default exports.
Disallow a lower specificity selector from coming after a higher specificity selector.
Disallow using a callback in asynchronous tests and hooks.
Disallow TypeScript enum.
Disallow exporting an imported variable.
Prevent usage of <head> element in a Next.js project.
Disallow implicit true values on JSX boolean attributes
Disallow type annotations for variables, parameters, and class properties initialized with a literal expression.
Disallow the use of TypeScript's namespaces.
Disallow negation in the condition of an if statement if it has an else clause.
Disallow nested ternary expressions.
Disallow non-null assertions using the ! postfix operator.
Disallow reassigning function parameters.
Disallow the use of parameter properties in class constructors.
Disallow the use of process.env.
This rule allows you to specify global variable names that you don’t want to use in your application.
Disallow specified modules when loaded by import or require.
Disallow user defined types.
Disallow the use of constants which its value is the upper-case version of its name.
Enforce the use of String.slice() over String.substr() and String.substring().
Disallow template literals if interpolation and special-character handling are not needed
Disallow else block when the if block breaks early.
Disallow use of @value rule in css modules.
Disallow the use of yoda expressions.
It enables the recommended rules for this group
Disallow Array constructors.
Enforce the use of as const over literal type and type annotation.
Use at() instead of integer index access.
Requires following curly brace conventions.
Enforce using else if instead of nested if in else clauses.
Enforce using single if instead of nested if clauses.
Enforce declaring components only within modules that export React Components exclusively.
Require consistently using either T[] or Array<T>
Enforce the use of new for all builtins, except String, Number and Boolean.
This rule enforces consistent use of curly braces inside JSX attributes and JSX children.
Require consistent accessibility modifiers on class properties and methods.
Require const declarations for variables that are only assigned once.
Enforce default function parameters and optional function parameters to be last.
Require the default clause in switch statements.
Require specifying the reason argument when using @deprecated directive
Require that each enum member value be explicitly initialized.
Enforce explicitly comparing the length, size, byteLength or byteOffset property of a value.
Disallow the use of Math.pow in favor of the ** operator.
Promotes the use of export type for types.
Enforce naming conventions for JavaScript and TypeScript filenames.
This rule recommends a for-of loop when in a for loop, the index used to extract an item from the iterated array.
This rule enforces the use of <>...</> over <Fragment>...</Fragment>.
Promotes the use of import type for types.
Require all enum members to be literal values.
Enforce naming conventions for everything across a codebase.
Promotes the usage of node:assert/strict over node:assert.
Enforces using the node: protocol for Node.js builtin modules.
Use the Number properties instead of global ones.
Prevent extra closing tags for components without children.
Require assignment operator shorthand where possible.
Enforce using function types instead of object type with call signatures.
Disallow multiple variable declarations in the same variable statement
Prefer template literals over string concatenation.
Require new when throwing an error.
Disallow throwing non-Error values.
Enforce the use of String.trimStart() and String.trimEnd() over String.trimLeft() and String.trimRight().
Rule's options.
A list of rules that belong to this group
Use standard constants instead of approximated literals.
Discourage the usage of Array index in keys.
Disallow assignments in expressions.
Disallows using an async function as a Promise executor.
Disallow reassigning exceptions in catch clauses.
Disallow reassigning class members.
Prevent comments from being inserted as text nodes
Disallow comparing against -0
Disallow labeled statements that are not loops.
Disallow void type outside of generic or return types.
Disallow the use of console.
Disallow TypeScript const enum
Prevents from having control characters and some escape sequences that match control characters in regular expression literals.
Disallow the use of debugger
Disallow direct assignments to document.cookie.
Prevents importing next/document outside of pages/_document.jsx in Next.js projects.
Require the use of === and !==.
Disallow duplicate @import rules.
Disallow duplicate case labels.
Disallow duplicate class members.
Disallow duplicate custom properties within declaration blocks.
Disallow duplicate conditions in if-else-if chains
No duplicated fields in GraphQL operations.
Disallow duplicate names within font families.
Prevents JSX properties to be assigned multiple times.
Disallow two keys with the same name inside objects.
Disallow duplicate function parameter name.
Disallow duplicate properties within declaration blocks.
Disallow duplicate selectors within keyframe blocks.
A describe block should not contain duplicate hooks.
Disallow CSS empty blocks.
Disallow empty block statements and static blocks.
Disallow the declaration of empty interfaces.
Disallow variables from evolving into any type through reassignments.
Disallow the any type usage.
Disallow using export or module.exports in files containing tests
Prevents the wrong usage of the non-null assertion operator (!) in TypeScript files.
Disallow fallthrough of switch clauses.
Disallow focused tests.
Disallow reassigning function declarations.
Disallow assignments to native objects and read-only global variables.
Use Number.isFinite instead of global isFinite.
Use Number.isNaN instead of global isNaN.
Prevent using the next/head module in pages/_document.js on Next.js projects.
Disallow use of implicit any type on variable declarations.
Disallow assigning to imported bindings
Disallow invalid !important within keyframe declarations
Disallows the use of irregular whitespace characters.
Disallow labels that share a name with a variable
Disallow characters made with multiple code points in character class syntax.
Enforce proper usage of new and constructor.
Checks that the assertion function, for example expect, is placed inside an it() function call.
Disallow shorthand assign when variable appears on both sides.
Disallow octal escape sequences in string literals
Disallow direct use of Object.prototype builtins.
Prevents React-specific JSX properties from being used.
Disallow variable, function, class, and type redeclarations in the same scope.
Prevents from having redundant "use strict".
Disallow comparisons where both sides are exactly the same.
Disallow identifiers from shadowing restricted names.
Disallow shorthand properties that override related longhand properties.
Disallow disabled tests.
Prevents the use of sparse arrays (arrays with holes).
It detects possible "wrong" semicolons inside JSX elements.
Disallow template literal placeholder syntax in regular strings.
Disallow then property.
Disallow unsafe declaration merging between interfaces and classes.
Disallow using unsafe negation.
Disallow the use of var
Disallow with statements in non-strict contexts.
It enables the recommended rules for this group
Disallow the use of overload signatures that are not next to each other.
Ensure async functions utilize await.
Enforce default clauses in switch statements to be last
Enforce passing a message value when creating a built-in error.
Enforce get methods to always return a value.
Enforces the use of a recommended display strategy with Google Fonts.
Require for-in loops to include an if statement.
Use Array.isArray() instead of instanceof Array.
Require using the namespace keyword over the module keyword to declare TypeScript namespaces.
Enforce using the digits argument with Number#toFixed().
Enforce the use of the directive "use strict" in script files.
Print trailing commas wherever possible in multi-line comma-separated syntactic structures.
Check undeclared types.
Allows the export of constants. This option is for environments that support it, such as Vite
A list of names that can be additionally exported from the module This option is for exports that do not hinder React Fast Refresh, such as meta in Remix
Options for the rule useExhaustiveDependencies
Whether to report an error when a hook has no dependencies array.
Whether to report an error when a dependency is listed in the dependencies array but isn't used. Defaults to true.
If true, the suggested extension is always .js regardless of what extension the source file has in your project.
Set to true to check shorthand fragments (<></>)
Options for the useSelfClosingElements rule.
input like custom components that should be checked.
[]Additional attributes that will be sorted.
Names of the functions or tagged templates that will be sorted.
[]Set of properties to integrate Biome with a VCS software.
The kind of client.
The main branch of the project
Whether Biome should integrate itself with the VCS client
The folder where Biome should check for VCS files. By default, Biome will use the same folder where biome.json was found.
If Biome can't find the configuration, it will attempt to use the current working directory. If no current working directory can't be found, Biome won't use the VCS integration, and a diagnostic will be emitted
Whether Biome should use the VCS ignore file. When [true], Biome will ignore the files specified in the ignore file.
Whitespace sensitivity for HTML formatting.
The following two cases won't produce the same output:
| | html | output | | -------------- | :------------: | :----------: | | with spaces | 1<b> 2 </b>3 | 1 2 3 | | without spaces | 1<b>2</b>3 | 123 |
This happens because whitespace is significant in inline elements.
As a consequence of this, the formatter must format blocks that look like this (assume a small line width, <20): html <span>really long content</span> as this, where the content hugs the tags: html <span >really long content</span >
Note that this is only necessary for inline elements. Block elements do not have this restriction.