From biome
Applies Biome linting for accessibility, complexity, correctness rules and code quality enforcement in JavaScript/TypeScript projects via check commands and config.
npx claudepluginhub thebushidocollective/han --plugin biomeThis skill is limited to using the following tools:
Expert knowledge of Biome's linting capabilities, rule categories, and code quality enforcement for JavaScript and TypeScript projects.
Lints and formats JS/TS/JSX/CSS/GraphQL code using Biome 2.4 with type-aware linting, GritQL rules, import organization, and ESLint/Prettier migrations. Use for config, CI checks, and custom rules.
Guides Biome 2.4 configuration for linting, formatting, and import organization in JavaScript, TypeScript, JSX, CSS, GraphQL. Covers type-aware linting, GritQL rules, ESLint/Prettier migration, IDE/CI setup.
Provides Biome commands for formatting, linting, and organizing imports in JavaScript, TypeScript, JSX/TSX, JSON, CSS projects. Use for zero-config setup, fast CI checks, or ESLint/Prettier migration.
Share bugs, ideas, or general feedback.
Expert knowledge of Biome's linting capabilities, rule categories, and code quality enforcement for JavaScript and TypeScript projects.
Biome's linter provides fast, comprehensive code quality checks with a focus on correctness, performance, security, and best practices. It's designed to catch common bugs and enforce consistent code patterns.
# Check files without fixing
biome check .
# Check and auto-fix
biome check --write .
# Check specific files
biome check src/**/*.ts
# CI mode (strict, fails on warnings)
biome ci .
# Verbose output
biome check --verbose .
# JSON output
biome check --json .
# Only lint (skip formatting)
biome lint .
# Apply safe fixes only
biome check --write --unsafe=false .
Rules for web accessibility and WCAG compliance:
{
"linter": {
"rules": {
"a11y": {
"recommended": true,
"noAccessKey": "error",
"noAriaHiddenOnFocusable": "error",
"noAutofocus": "warn",
"noBlankTarget": "error",
"noPositiveTabindex": "error",
"useAltText": "error",
"useAnchorContent": "error",
"useButtonType": "error",
"useValidAriaProps": "error"
}
}
}
}
Common violations:
Rules to reduce code complexity:
{
"linter": {
"rules": {
"complexity": {
"recommended": true,
"noBannedTypes": "error",
"noExcessiveCognitiveComplexity": "warn",
"noExtraBooleanCast": "error",
"noMultipleSpacesInRegularExpressionLiterals": "error",
"noUselessCatch": "error",
"noUselessConstructor": "error",
"noUselessEmptyExport": "error",
"noUselessFragments": "error",
"noUselessLabel": "error",
"noUselessRename": "error",
"noUselessSwitchCase": "error",
"noWith": "error"
}
}
}
}
Rules for code correctness and bug prevention:
{
"linter": {
"rules": {
"correctness": {
"recommended": true,
"noChildrenProp": "error",
"noConstAssign": "error",
"noConstantCondition": "error",
"noConstructorReturn": "error",
"noEmptyPattern": "error",
"noGlobalObjectCalls": "error",
"noInnerDeclarations": "error",
"noInvalidConstructorSuper": "error",
"noNewSymbol": "error",
"noNonoctalDecimalEscape": "error",
"noPrecisionLoss": "error",
"noSelfAssign": "error",
"noSetterReturn": "error",
"noSwitchDeclarations": "error",
"noUndeclaredVariables": "error",
"noUnreachable": "error",
"noUnreachableSuper": "error",
"noUnsafeFinally": "error",
"noUnsafeOptionalChaining": "error",
"noUnusedLabels": "error",
"noUnusedVariables": "error",
"useIsNan": "error",
"useValidForDirection": "error",
"useYield": "error"
}
}
}
}
Critical rules:
noUndeclaredVariables: Catch undeclared variablesnoUnusedVariables: Remove unused codenoConstAssign: Prevent const reassignmentnoUnreachable: Detect unreachable codeuseIsNan: Use isNaN() for NaN checksRules for performance optimization:
{
"linter": {
"rules": {
"performance": {
"recommended": true,
"noAccumulatingSpread": "warn",
"noDelete": "error"
}
}
}
}
Rules for security best practices:
{
"linter": {
"rules": {
"security": {
"recommended": true,
"noDangerouslySetInnerHtml": "error",
"noDangerouslySetInnerHtmlWithChildren": "error",
"noGlobalEval": "error"
}
}
}
}
Critical security rules:
Code style and consistency rules:
{
"linter": {
"rules": {
"style": {
"recommended": true,
"noArguments": "error",
"noCommaOperator": "error",
"noImplicitBoolean": "warn",
"noNegationElse": "warn",
"noNonNullAssertion": "warn",
"noParameterAssign": "error",
"noRestrictedGlobals": "error",
"noShoutyConstants": "warn",
"noUnusedTemplateLiteral": "error",
"noVar": "error",
"useBlockStatements": "warn",
"useCollapsedElseIf": "warn",
"useConst": "error",
"useDefaultParameterLast": "error",
"useEnumInitializers": "warn",
"useExponentiationOperator": "error",
"useFragmentSyntax": "error",
"useNumericLiterals": "error",
"useSelfClosingElements": "error",
"useShorthandArrayType": "error",
"useSingleVarDeclarator": "error",
"useTemplate": "warn",
"useWhile": "error"
}
}
}
}
Key style rules:
noVar: Use let/const instead of varuseConst: Prefer const for immutable bindingsnoNonNullAssertion: Avoid ! assertions in TypeScriptuseTemplate: Prefer template literalsRules for suspicious code patterns:
{
"linter": {
"rules": {
"suspicious": {
"recommended": true,
"noArrayIndexKey": "warn",
"noAssignInExpressions": "error",
"noAsyncPromiseExecutor": "error",
"noCatchAssign": "error",
"noClassAssign": "error",
"noCommentText": "error",
"noCompareNegZero": "error",
"noConsoleLog": "warn",
"noControlCharactersInRegex": "error",
"noDebugger": "error",
"noDoubleEquals": "error",
"noDuplicateCase": "error",
"noDuplicateClassMembers": "error",
"noDuplicateObjectKeys": "error",
"noDuplicateParameters": "error",
"noEmptyBlockStatements": "warn",
"noExplicitAny": "warn",
"noExtraNonNullAssertion": "error",
"noFallthroughSwitchClause": "error",
"noFunctionAssign": "error",
"noGlobalAssign": "error",
"noImportAssign": "error",
"noLabelVar": "error",
"noMisleadingCharacterClass": "error",
"noPrototypeBuiltins": "error",
"noRedeclare": "error",
"noSelfCompare": "error",
"noShadowRestrictedNames": "error",
"noUnsafeNegation": "error",
"useDefaultSwitchClauseLast": "error",
"useGetterReturn": "error",
"useValidTypeof": "error"
}
}
}
}
Critical suspicious patterns:
noExplicitAny: Avoid any in TypeScriptnoConsoleLog: Remove console.log in productionnoDebugger: Remove debugger statementsnoDoubleEquals: Use === instead of ==noDuplicateObjectKeys: Catch duplicate keysMaximum strictness for high-quality codebases:
{
"linter": {
"enabled": true,
"rules": {
"recommended": true,
"a11y": { "recommended": true },
"complexity": { "recommended": true },
"correctness": { "recommended": true },
"performance": { "recommended": true },
"security": { "recommended": true },
"style": { "recommended": true },
"suspicious": {
"recommended": true,
"noExplicitAny": "error",
"noConsoleLog": "error"
}
}
}
}
Start lenient and progressively tighten:
{
"linter": {
"enabled": true,
"rules": {
"recommended": true,
"suspicious": {
"noExplicitAny": "warn",
"noConsoleLog": "warn"
},
"style": {
"noVar": "error",
"useConst": "warn"
}
}
}
}
React configuration example:
{
"linter": {
"rules": {
"recommended": true,
"a11y": { "recommended": true },
"correctness": {
"recommended": true,
"noChildrenProp": "error"
},
"security": {
"noDangerouslySetInnerHtml": "error"
},
"suspicious": {
"noArrayIndexKey": "error"
}
}
}
}
Suppress specific violations:
// biome-ignore lint/suspicious/noExplicitAny: Legacy code
function legacyFunction(data: any) {
return data;
}
// biome-ignore lint/suspicious/noConsoleLog: Debug logging
console.log('Debug info');
// Multiple rules
// biome-ignore lint/suspicious/noExplicitAny lint/style/useConst: Migration
var config: any = {};
Ignore entire file:
/* biome-ignore-file */
// Legacy file, skip all linting
Ignore patterns in biome.json:
{
"files": {
"ignore": [
"**/generated/**",
"**/*.config.js",
"**/vendor/**"
]
}
}
"recommended": truebiome ci in pipelinesCreate shared rule sets for organization:
{
"extends": ["@company/biome-config"],
"linter": {
"rules": {
"suspicious": {
"noConsoleLog": "error"
}
}
}
}
Use overrides for different code areas:
{
"overrides": [
{
"include": ["src/**/*.ts"],
"linter": {
"rules": {
"suspicious": {
"noExplicitAny": "error"
}
}
}
},
{
"include": ["scripts/**/*.js"],
"linter": {
"rules": {
"suspicious": {
"noConsoleLog": "off"
}
}
}
}
]
}
Migrating from ESLint:
npm install -D @biomejs/biomenpx biome initnpx biome check . to see violationsnpx biome check --write .{
"scripts": {
"lint": "biome check .",
"lint:fix": "biome check --write .",
"lint:ci": "biome ci ."
}
}
Using husky:
{
"husky": {
"hooks": {
"pre-commit": "biome check --write --changed"
}
}
}
- name: Run Biome
run: npx biome ci .
If rule triggers incorrectly:
If linting is slow:
Verify: