recommended

The default config. It turns on Biome’s recommended rule set, then changes the rules listed below.

Usage

biome.json

{
  "extends": ["@repobuddy/biome"]
}

@repobuddy/biome/recommended resolves to the same file, recommended.jsonc.

Options

None. The config takes no parameters. Override settings in your own biome.json (see Override a rule or formatter setting).

Effective config

This is the content of packages/biome/recommended.jsonc with the comments shortened.

{
  "files": {
    "includes": ["**", "!**/.vscode/**/*.txt", "!**/*.md"]
  },
  "formatter": {
    "enabled": true,
    "indentStyle": "tab",
    "lineEnding": "lf",
    "lineWidth": 120
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single",
      "semicolons": "asNeeded"
    }
  },
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true,
      "complexity": {
        "noForEach": "off",
        "useLiteralKeys": "off",
        "noCommaOperator": "off"
      },
      "correctness": {
        "noUnusedImports": { "level": "error", "fix": "safe" },
        "noUnusedVariables": { "level": "error", "options": { "ignoreRestSiblings": true } },
        "useExhaustiveDependencies": "off"
      },
      "style": {
        "noNonNullAssertion": "off",
        "noParameterAssign": "off",
        "useTemplate": "off",
        "useAsConstAssertion": "error",
        "useDefaultParameterLast": "error",
        "useEnumInitializers": "error",
        "useSelfClosingElements": "error",
        "useSingleVarDeclarator": "error",
        "noUnusedTemplateLiteral": "error",
        "useNumberNamespace": "error",
        "noInferrableTypes": "error",
        "noUselessElse": "error",
        "useNodejsImportProtocol": "error"
      },
      "suspicious": {
        "noAssignInExpressions": "off",
        "noExplicitAny": "off",
        "noConsole": {
          "level": "error",
          "options": {
            "allow": [
              "info", "warn", "error", "assert", "table", "clear", "count", "countReset", "debug",
              "dir", "dirxml", "group", "groupCollapsed", "groupEnd", "time", "timeEnd", "timeLog",
              "trace", "profile", "profileEnd", "timeStamp"
            ]
          }
        },
        "noVar": "warn"
      }
    }
  },
  "assist": { "actions": { "source": { "organizeImports": "on" } } },
  "overrides": [
    {
      "includes": [
        "**/frontmatter.json",
        "**/.frontmatter/config/**/*.json",
        "**/.vscode/**/*.json",
        "**/tsconfig*.json"
      ],
      "json": { "parser": { "allowComments": true, "allowTrailingCommas": true } }
    },
    {
      "includes": ["**/package.json"],
      "formatter": { "lineWidth": 20 }
    }
  ]
}

Files

Setting	Value
files.includes	**, minus **/.vscode/**/*.txt and **/*.md

Markdown is excluded because Biome 2.4.15 rewrote YAML frontmatter as Markdown headings. Biome 2.5 does not process Markdown, so the exclusion has no effect today.

Formatter

Setting	Value
formatter.enabled	true
formatter.indentStyle	tab
formatter.lineEnding	lf
formatter.lineWidth	120
javascript.formatter.quoteStyle	single
javascript.formatter.semicolons	asNeeded
javascript.formatter.trailingCommas	not set (Biome default, all)
**/package.json formatter.lineWidth	20, so the output matches sort-package-json

Linter

linter.enabled is true and recommended is true. The table lists every rule the config changes. The last column is the level Biome 2.5.15 reported for the same code with an empty config ({}); “not reported” means it produced no diagnostic.

Rule	Level	Options	Biome default (2.5.15)	What it flags
complexity/noForEach	off	none	not reported	.forEach() calls
complexity/useLiteralKeys	off	none	info	x['y'] instead of x.y
complexity/noCommaOperator	off	none	warn	(1, 2)
correctness/noUnusedImports	error	fix: safe	warn	Imports never used
correctness/noUnusedVariables	error	ignoreRestSiblings: true	warn	Variables never read
correctness/useExhaustiveDependencies	off	none	not reported	React hook dependency lists
style/noNonNullAssertion	off	none	warn	value!
style/noParameterAssign	off	none	not reported	Assigning to a parameter
style/useTemplate	off	none	info	a + 'b' instead of a template
style/useAsConstAssertion	error	none	not reported	1 as 1 instead of as const
style/useDefaultParameterLast	error	none	not reported	A default parameter before a required one
style/useEnumInitializers	error	none	not reported	Enum members without initializers
style/useSelfClosingElements	error	none	not reported	<div></div>
style/useSingleVarDeclarator	error	none	not reported	const a = 1, b = 2
style/noUnusedTemplateLiteral	error	none	not reported	A template literal with no interpolation
style/useNumberNamespace	error	none	not reported	parseInt, isNaN instead of Number.*
style/noInferrableTypes	error	none	not reported	const x: number = 1
style/noUselessElse	error	none	not reported	else after return
style/useNodejsImportProtocol	error	none	info	'assert' instead of 'node:assert'
suspicious/noAssignInExpressions	off	none	error	if ((x = 1))
suspicious/noExplicitAny	off	none	warn	: any
suspicious/noConsole	error	allow: every console method except log	not reported	console.log()
suspicious/noVar	warn	none	not reported	var

useNodejsImportProtocol is info in Biome, which prints the finding and exits 0. The config raises it to error so it fails the run. The node: prefix distinguishes a builtin from a package of the same name on the registry.

The noConsole allow list is: info, warn, error, assert, table, clear, count, countReset, debug, dir, dirxml, group, groupCollapsed, groupEnd, time, timeEnd, timeLog, trace, profile, profileEnd, and timeStamp.

Assist

Action	Value
assist.actions.source.organizeImports	on

Overrides

includes	Effect
**/frontmatter.json, **/.frontmatter/config/**/*.json, **/.vscode/**/*.json, **/tsconfig*.json	json.parser.allowComments and allowTrailingCommas are true
**/package.json	formatter.lineWidth is 20

Examples

Each fixture under packages/biome/tests/recommended exercises one rule. The command pnpm --filter @repobuddy/biome check:preset lints them with --error-on-warnings. A rule that stops firing leaves an unused biome-ignore, which fails that command.

Flagged at error (the fixture carries a biome-ignore for the rule):

// style/useNodejsImportProtocol
import { deepEqual } from 'assert'

// suspicious/noConsole
console.log()

// correctness/noUnusedImports
import { deepEqual } from 'node:assert'

// correctness/noUnusedVariables
const unusedVar = 0

Flagged at warn:

// suspicious/noVar
export function hello(): string {
  var greeting = 'Hello World!'
  return greeting
}

Accepted because the rule is off:

// complexity/noForEach
;[].forEach((x) => void console.info(x))

// complexity/useLiteralKeys, with an index signature in the type
console.info(x['y'])

// style/useTemplate
export const s = foo + 'b'

// correctness/useExhaustiveDependencies: functions need not be listed as dependencies
useEffect(() => {
  fn()
}, [])

Accepted console methods (fixture suspicious/no_console_log.ts): info, warn, error, assert, table, clear, count, countReset, debug, dir, dirxml, group, groupCollapsed, groupEnd, time, timeEnd, timeLog, trace, profile, profileEnd, and timeStamp.

The fixture formatter/tailing_comma.ts shows the formatter’s output: multi-line parameter lists end with a trailing comma.

Related

• performant and recommended vs performant
• Override a rule or formatter setting
• Biome configuration reference