Biome Configurations

Installation

npm:

npm install -D @dvashim/biome-config

or pnpm:

pnpm add -D @dvashim/biome-config

Configurations

| Domain | Level | Path | |--------|------------|------| | Base | recommended | @dvashim/biome-config or @dvashim/biome-config/recommended | | React | recommended | @dvashim/biome-config/react-recommended | | React | balanced | @dvashim/biome-config/react-balanced | | React | strict | @dvashim/biome-config/react-strict |

Use

Base recommended configuration:

// biome.json (Base recommended)
// This configuration provides a base setup for linting,
// formatting, and code consistency across JavaScript,
// JSX, JSON, and HTML files.
// No files.includes is set — Biome will process all supported
// files in the project directory by default.

{
  "extends": ["@dvashim/biome-config"]
}

React recommended configuration:

// biome.json (React recommended)
// This configuration extends the base recommended configuration
// and enables the recommended rules for the React domain.
// Includes all files except dist/ (files.includes: ["**", "!!**/dist"]).

{
  "extends": ["@dvashim/biome-config/react-recommended"]
}

React strict configuration:

// biome.json (React strict)
// This configuration enables recommended lint rules,
// including React-specific recommended rules,
// and opts into nursery (experimental) rules.
// Includes all files except dist/ (files.includes: ["**", "!!**/dist"]).

{
  "extends": ["@dvashim/biome-config/react-strict"]
}

React balanced configuration:

// biome.json (React balanced)
// This configuration enables recommended lint rules,
// including React-specific recommended rules,
// with a few rules intentionally disabled
// to reduce false positives / noise.
// Includes all files except dist/ (files.includes: ["**", "!!**/dist"]).

{
  "extends": ["@dvashim/biome-config/react-balanced"]
}

Defaults

All configurations share the same base defaults.

Schema

https://biomejs.dev/schemas/2.4.10/schema.json

Formatter

| Option | Value | |--------|-------| | attributePosition | "auto" | | bracketSameLine | false | | bracketSpacing | true | | expand | "auto" | | formatWithErrors | false | | indentStyle | "space" | | indentWidth | 2 | | lineEnding | "lf" | | lineWidth | 80 | | useEditorconfig | true |

JavaScript

| Option | Value | |--------|-------| | experimentalEmbeddedSnippetsEnabled | true | | jsxRuntime | "transparent" |

JavaScript Formatter

| Option | Value | |--------|-------| | arrowParentheses | "always" | | jsxQuoteStyle | "double" | | operatorLinebreak | "before" | | quoteProperties | "asNeeded" | | quoteStyle | "single" | | semicolons | "asNeeded" | | trailingCommas | "es5" |

JSON

| Option | Value | |--------|-------| | allowComments | true | | allowTrailingCommas | true |

HTML

| Option | Value | |--------|-------| | experimentalFullSupportEnabled | true |

Files (React configs only)

| Option | Value | |--------|-------| | includes | ["**", "!!**/dist"] |

VCS

| Option | Value | |--------|-------| | clientKind | "git" | | enabled | true | | defaultBranch | "main" | | useIgnoreFile | true |

Overrides

| File pattern | Setting | Value | |----------------|--------------------------------------|------------| | package.json | assist.actions.source.useSortedKeys | "off" | | package.json | json.formatter.expand | "always" |

Assist

| Option | Value | |--------|-------| | actions.recommended | true | | actions.source.noDuplicateClasses | "on" |

Rules

Base recommended

Enables all recommended Biome rules out of the box with no custom overrides. Provides sensible defaults for code quality, correctness, and best practices across JavaScript, JSX, JSON, and HTML.

React recommended

Same as base recommended, plus enables the React domain ("react": "recommended"), which activates React-specific recommended rules for hooks, JSX, and component patterns.

React strict

The most opinionated configuration. Enables all recommended rules plus 180+ optional and nursery rules across 8 categories. Every non-recommended JS/TS rule available in Biome is explicitly configured.

• a11y — Selectively disables noisy rules (useButtonType, useKeyWithClickEvents, useSemanticElements, noStaticElementInteractions, noNoninteractiveElementToInteractiveRole) while keeping the rest at recommended defaults.

• complexity (12 rules) — Monitors cognitive complexity, function length, nested test suites, and logic expressions. Warns on forEach, implicit coercions, void, and useless patterns.

• correctness (12 rules) — Ensures no undeclared variables/dependencies, proper React patterns (noReactPropAssignments, noNestedComponentDefinitions), Node.js guards (noNodejsModules, noProcessGlobal, noGlobalDirnameFilename), and JSON import attributes. noUnresolvedImports is disabled since TypeScript already performs these checks.

• nursery (73 rules) — Opts into all experimental rules. Highlights include:

  • Errors: noJsxPropsBind, noLeakedRender, noMisusedPromises, noMultiAssign, noParametersOnlyUsedInRecursion
  • Promises: noFloatingPromises, noNestedPromises, useAwaitThenable
  • TypeScript: useConsistentEnumValueType, useConsistentMethodSignatures, useExhaustiveSwitchCases, useNullishCoalescing
  • Regex: useNamedCaptureGroup, useUnicodeRegex, useRegexpExec
  • Styling: noDuplicateSelectors, noInlineStyles
  • Playwright: Full suite of 10 Playwright rules
  • Drizzle: noDrizzleDeleteWithoutWhere, noDrizzleUpdateWithoutWhere
  • Tailwind: useSortedClasses, noFloatingClasses
  • Dependencies: noUntrustedLicenses
  • Disabled: noTernary, useExplicitType

• performance (6 rules) — Warns on await in loops, barrel files, delete, namespace imports, re-export all, and non-top-level regex.

• security — noSecrets

• style (56 rules) — Enforces consistent syntax, naming conventions (strictCase: true), array shorthand syntax, type over interface, React function components, readonly class properties, noDefaultExport, noMagicNumbers, noJsxLiterals, and more.

• suspicious (22 rules) — Flags var (error), console, alert, bitwise operators, empty blocks, import cycles, evolving types, skipped tests, and deprecated imports.

React balanced

Same rule set as strict, with targeted relaxations to reduce false positives and noise in real-world projects:

| Rule | Strict | Balanced | Reason | |------|--------|----------|--------| | noImplicitCoercions | warn | off | Too noisy with !!value patterns | | noExcessiveLinesPerFunction | warn (default) | warn (maxLines: 100) | Higher threshold | | noContinue | warn | info | Informational only | | noIncrementDecrement | warn | warn (allowForLoopAfterthoughts) | Allows i++ in for loops | | noUselessReturn | warn | info | Informational only | | noBarrelFile | warn | off | Common pattern in libraries | | noNamespaceImport | warn | off | Allows import * as | | noReExportAll | warn | off | Common pattern in libraries | | noDefaultExport | warn | off | Allows default exports | | noImplicitBoolean | warn | info | Informational only | | noJsxLiterals | warn | off | Allows inline text in JSX | | noMagicNumbers | warn | info | Informational only | | noNestedTernary | warn | off | Allows nested ternaries | | useNamingConvention | strictCase: true | strictCase: false | More lenient casing |

FAQ

Which config should I start with?

• Non-React projects — use @dvashim/biome-config (base recommended).
• React projects — start with react-balanced for a good trade-off between strictness and practicality. Move to react-strict once your codebase is clean, or react-recommended if you only want Biome's built-in defaults.

How do I override a rule from the preset?

Add a linter.rules section in your biome.json. Local settings merge with and take precedence over the preset:

{
  "extends": ["@dvashim/biome-config/react-balanced"],
  "linter": {
    "rules": {
      "style": {
        "noDefaultExport": "error"
      }
    }
  }
}

How do I exclude additional files or directories?

The simplest approach is to add paths to your .gitignore — all presets enable vcs.useIgnoreFile, so Biome respects .gitignore patterns automatically.

For exclusions that should not affect Git tracking, use negated patterns in files.includes. The !! prefix force-ignores paths (prevents scanning entirely), while ! excludes matches from results:

{
  "extends": ["@dvashim/biome-config"],
  "files": {
    "includes": ["**", "!!**/generated", "!!**/coverage"]
  }
}

Why does the base config not set files.includes?

The base recommended config intentionally omits files.includes so consumers control their own file scope. Biome processes all supported files by default when no includes is set. The React configs set files.includes to ["**", "!!**/dist"] to explicitly exclude build output.

Can I use this with TypeScript?

Yes. Biome natively supports TypeScript — no additional configuration is needed. All presets apply to .ts and .tsx files automatically.

Can I use this in a monorepo?

Yes. Install the package at the root and reference it in each workspace's biome.json. Each workspace can extend a different preset and add its own overrides.