Biome

https://v1.biomejs.dev/
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### Install Biome using bun

Source: https://v1.biomejs.dev/guides/getting-started

Installs Biome as a development dependency using bun.

```bash
bun add --dev --exact @biomejs/biome
```

--------------------------------

### Install Biome using deno

Source: https://v1.biomejs.dev/guides/getting-started

Installs Biome as a development dependency using deno.

```bash
deno add --dev npm:@biomejs/biome
```

--------------------------------

### Initialize Biome configuration using deno

Source: https://v1.biomejs.dev/guides/getting-started

Initializes a biome.json configuration file using deno.

```bash
deno run -A npm:@biomejs/biome init
```

--------------------------------

### Initialize Biome configuration using bun

Source: https://v1.biomejs.dev/guides/getting-started

Initializes a biome.json configuration file using bun.

```bash
bunx biome init
```

--------------------------------

### Install Biome using npm

Source: https://v1.biomejs.dev/guides/getting-started

Installs Biome as a development dependency using npm.

```bash
npm install --save-dev --save-exact @biomejs/biome
```

--------------------------------

### Initialize Biome configuration using npx

Source: https://v1.biomejs.dev/guides/getting-started

Initializes a biome.json configuration file using npx.

```bash
npx @biomejs/biome init
```

--------------------------------

### Install Biome using yarn

Source: https://v1.biomejs.dev/guides/getting-started

Installs Biome as a development dependency using yarn.

```bash
yarn add --dev --exact @biomejs/biome
```

--------------------------------

### Install Biome using pnpm

Source: https://v1.biomejs.dev/guides/getting-started

Installs Biome as a development dependency using pnpm.

```bash
pnpm add --save-dev --save-exact @biomejs/biome
```

--------------------------------

### Initialize Biome configuration using pnpm

Source: https://v1.biomejs.dev/guides/getting-started

Initializes a biome.json configuration file using pnpm.

```bash
pnpm biome init
```

--------------------------------

### Initialize Biome configuration using yarn

Source: https://v1.biomejs.dev/guides/getting-started

Initializes a biome.json configuration file using yarn.

```bash
yarn biome init
```

--------------------------------

### Format files using deno

Source: https://v1.biomejs.dev/guides/getting-started

Formats specified files or directories using the Biome CLI with deno.

```bash
deno run -A npm:@biomejs/biome format --write <files>
```

--------------------------------

### Default Biome configuration file

Source: https://v1.biomejs.dev/guides/getting-started

Example of a default biome.json configuration file generated by the init command.

```json
{
  "$schema": "https://biomejs.dev/schemas/1.9.4/schema.json",
  "vcs": {
    "enabled": false,
    "clientKind": "git",
    "useIgnoreFile": false
  },
  "files": { "ignoreUnknown": false, "ignore": [] },
  "formatter": { "enabled": true, "indentStyle": "tab" },
  "organizeImports": { "enabled": true },
  "linter": {
    "enabled": true,
    "rules": { "recommended": true }
  },
  "javascript": { "formatter": { "quoteStyle": "double" } }
}
```

--------------------------------

### Format files using npx

Source: https://v1.biomejs.dev/guides/getting-started

Formats specified files or directories using the Biome CLI with npx.

```bash
npx @biomejs/biome format --write <files>
```

--------------------------------

### Format files using bun

Source: https://v1.biomejs.dev/guides/getting-started

Formats specified files or directories using the Biome CLI with bun.

```bash
bunx biome format --write <files>
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-trim-start-end

Example of how to configure the useTrimStartEnd rule.

```json
{
  "linter": {
    "rules": {
      "nursery": {
        "useTrimStartEnd": "error"
      }
    }
  }
}
```

--------------------------------

### Format files using yarn

Source: https://v1.biomejs.dev/guides/getting-started

Formats specified files or directories using the Biome CLI with yarn.

```bash
yarn biome format --write <files>
```

--------------------------------

### Check files using deno

Source: https://v1.biomejs.dev/guides/getting-started

Runs format, lint, and organize imports on specified files or directories using the Biome CLI with deno.

```bash
deno run -A npm:@biomejs/biome check --write <files>
```

--------------------------------

### Format files using pnpm

Source: https://v1.biomejs.dev/guides/getting-started

Formats specified files or directories using the Biome CLI with pnpm.

```bash
pnpm biome format --write <files>
```

--------------------------------

### Check files using npx

Source: https://v1.biomejs.dev/guides/getting-started

Runs format, lint, and organize imports on specified files or directories using the Biome CLI with npx.

```bash
npx @biomejs/biome check --write <files>
```

--------------------------------

### Check files using bun

Source: https://v1.biomejs.dev/guides/getting-started

Runs format, lint, and organize imports on specified files or directories using the Biome CLI with bun.

```bash
bunx biome check --write <files>
```

--------------------------------

### Check files using pnpm

Source: https://v1.biomejs.dev/guides/getting-started

Runs format, lint, and organize imports on specified files or directories using the Biome CLI with pnpm.

```bash
pnpm biome check --write <files>
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-is-nan

This is an example of how to configure the useIsNan rule.

```json
{
  "linter": {
    "rules": {
      "correctness": {
        "useIsNan": "error"
      }
    }
  }
}
```

--------------------------------

### Check files using yarn

Source: https://v1.biomejs.dev/guides/getting-started

Runs format, lint, and organize imports on specified files or directories using the Biome CLI with yarn.

```bash
yarn biome check --write <files>
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-alt-text

Example of how to configure the `useAltText` rule in Biome.

```json
{
  "linter": {
    "rules": {
      "a11y": {
        "useAltText": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-nodejs-import-protocol

Example of how to configure the 'useNodejsImportProtocol' rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "style": {
        "useNodejsImportProtocol": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-useless-undefined-initialization

This is an example of how to configure the noUselessUndefinedInitialization rule in the linter configuration.

```json
{
  "linter": {
    "rules": {
      "complexity": {
        "noUselessUndefinedInitialization": "error"
      }
    }
  }
}
```

--------------------------------

### Docker Image Usage

Source: https://v1.biomejs.dev/guides/manual-installation

Examples of using Biome's official Docker images for linting and formatting files. The default working directory in the container is /code.

```bash
# Lint files
docker run -v $(pwd):/code ghcr.io/biomejs/biome lint
docker run -v $(pwd):/code ghcr.io/biomejs/biome lint --write


# Format files
docker run -v $(pwd):/code ghcr.io/biomejs/biome format
docker run -v $(pwd):/code ghcr.io/biomejs/biome format --write
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-positive-tabindex

This is an example of how to configure the `noPositiveTabindex` rule.

```json
{
  "linter": {
    "rules": {
      "a11y": {
        "noPositiveTabindex": "error"
      }
    }
  }
}
```

--------------------------------

### Lint and fix files using bun

Source: https://v1.biomejs.dev/guides/getting-started

Lints specified files or directories and applies safe fixes using the Biome CLI with bun.

```bash
bunx biome lint --write <files>
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-iframe-title

Example of how to configure the `useIframeTitle` rule in the Biome configuration.

```json
{
  "linter": {
    "rules": {
      "a11y": {
        "useIframeTitle": "error"
      }
    }
  }
}
```

--------------------------------

### Lint and fix files using deno

Source: https://v1.biomejs.dev/guides/getting-started

Lints specified files or directories and applies safe fixes using the Biome CLI with deno.

```bash
deno run -A npm:@biomejs/biome lint --write <files>
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-useless-switch-case

Example of how to configure the noUselessSwitchCase rule in a biome.json file.

```json
{
  "linter": {
    "rules": {
      "complexity": {
        "noUselessSwitchCase": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration Example

Source: https://v1.biomejs.dev/linter/rules/no-duplicate-at-import-rules

Example of how to configure the noDuplicateAtImportRules in biome.json.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noDuplicateAtImportRules": "error"
      }
    }
  }
}
```

--------------------------------

### Lint and fix files using npx

Source: https://v1.biomejs.dev/guides/getting-started

Lints specified files or directories and applies safe fixes using the Biome CLI with npx.

```bash
npx @biomejs/biome lint --write <files>
```

--------------------------------

### Homebrew Installation

Source: https://v1.biomejs.dev/guides/manual-installation

Installs Biome using the Homebrew package manager on macOS and Linux.

```bash
brew install biome
```

--------------------------------

### organizeImports.include example

Source: https://v1.biomejs.dev/reference/configuration

Example configuration for including files for import sorting.

```json
{
  "organizeImports": {
    "include": ["scripts/*.js"]
  }
}
```

--------------------------------

### Configuration Example

Source: https://v1.biomejs.dev/linter/rules/use-key-with-click-events

Example of how to configure the useKeyWithClickEvents rule in Biome.

```json
{
  "linter": {
    "rules": {
      "a11y": {
        "useKeyWithClickEvents": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-substr

Example of how to configure the noSubstr rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "nursery": {
        "noSubstr": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-self-assign

Example of how to configure the noSelfAssign rule in the Biome configuration.

```json
{
  "linter": {
    "rules": {
      "correctness": {
        "noSelfAssign": "error"
      }
    }
  }
}
```

--------------------------------

### Valid Example

Source: https://v1.biomejs.dev/linter/rules/use-jsx-key-in-iterable

This example shows valid usage with key props.

```jsx
[<Hello key="first" />, <Hello key="second" />, <Hello key="third" />];
data.map((x) => <Hello key={x.id}>{x}</Hello>);
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-heading-content

This is an example of how to configure the useHeadingContent rule in the linter configuration.

```json
{
  "linter": {
    "rules": {
      "a11y": {
        "useHeadingContent": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-class-assign

Example of how to configure the noClassAssign rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noClassAssign": "error"
      }
    }
  }
}
```

--------------------------------

### Example ESLint configuration

Source: https://v1.biomejs.dev/guides/migrate-eslint-prettier

An example ESLint configuration file.

```json
{
  "extends": ["plugin:unicorn/recommended"],
  "plugins": ["unicorn"],
  "ignore_patterns": ["dist/**"],
  "globals": {
    "Global1": "readonly"
  },
  "rules": {
    "eqeqeq": "error"
  },
  "overrides": [
    {
      "files": ["tests/**"],
      "rules": {
        "eqeqeq": "off"
      }
    }
  ]
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-duplicate-else-if

This example shows how to configure the noDuplicateElseIf rule.

```json
{
  "linter": {
    "rules": {
      "nursery": {
        "noDuplicateElseIf": "error"
      }
    }
  }
}
```

--------------------------------

### Simplified private class member convention

Source: https://v1.biomejs.dev/linter/rules/use-naming-convention

Example of configuring a convention for private class members to start with an underscore.

```json
{
    // ...
    "options": {
        "conventions": [
            {
                "selector": {
                    "kind": "classMember",
                    "modifiers": ["private"]
                },
                "match": "_(.+)"
                // We don't need to specify `formats` because the capture is forwarded to the next conventions.
            }
            // default conventions
        ]
    }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-constant-condition

Example of how to configure the noConstantCondition rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "correctness": {
        "noConstantCondition": "error"
      }
    }
  }
}

```

--------------------------------

### How to configure

Source: https://v1.biomejs.dev/linter/rules/use-filenaming-convention

Example of how to configure the rule.

```json
{
  "linter": {
    "rules": {
      "style": {
        "useFilenamingConvention": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-catch-assign

This is an example of how to configure the noCatchAssign rule in a biome.json file.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noCatchAssign": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-self-compare

Example of how to configure the noSelfCompare rule in Biome.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noSelfCompare": "error"
      }
    }
  }
}
```

--------------------------------

### Windows (x86_64) Binary Installation

Source: https://v1.biomejs.dev/guides/manual-installation

Downloads the Biome executable for Windows x86_64 architecture.

```powershell
# Windows (x86_64, Powershell)
Invoke-WebRequest -Uri "https://github.com/biomejs/biome/releases/download/cli%2Fv<version>/biome-win32-x64.exe" -OutFile "biome.exe"
```

--------------------------------

### noUndeclaredDependencies now recognizes imports of subpath exports

Source: https://v1.biomejs.dev/internals/changelog

Example import statements that no longer report errors if @mui/material and tailwindcss are installed as dependencies.

```typescript
import Button from "@mui/material/Button";
import { fontFamily } from "tailwindcss/defaultTheme";
```

--------------------------------

### Using 'extends' to resolve shared configuration

Source: https://v1.biomejs.dev/blog/biome-v1-6

Example of how to use the 'extends' property in biome.json to reference a shared configuration from an installed dependency.

```json
{
  "extends": ["@shared-configs/biome"]
}
```

--------------------------------

### Options

Source: https://v1.biomejs.dev/linter/rules/use-filenaming-convention

Example of how to configure the rule options.

```json
{
    "//": "...",
    "options": {
        "strictCase": false,
        "requireAscii": true,
        "filenameCases": ["camelCase", "export"]
    }
}
```

--------------------------------

### Enforce naming conventions for private class members

Source: https://v1.biomejs.dev/linter/rules/use-naming-convention

Example of enforcing that private class members start with `_` and the captured name is in `camelCase`.

```json
{
    "//": "...",
    "options": {
        "conventions": [
            {
                "selector": {
                    "kind": "classMember",
                    "modifiers": ["private"]
                },
                "match": "_(.+)",
                "formats": ["camelCase"]
            }
        ]
    }
}
```

--------------------------------

### Husky: Prepare script for automatic hook setup

Source: https://v1.biomejs.dev/recipes/git-hooks

This `package.json` script automatically sets up Husky hooks upon package installation.

```json
{
  "scripts": {
    "prepare": "husky"
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-parameter-assign

This is an example of how to configure the noParameterAssign rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "style": {
        "noParameterAssign": "error"
      }
    }
  }
}
```

--------------------------------

### Linux (x86_64) Binary Installation

Source: https://v1.biomejs.dev/guides/manual-installation

Downloads and makes the Biome executable for Linux x86_64 architecture executable.

```bash
# Linux (x86_64)
curl -L https://github.com/biomejs/biome/releases/download/cli%2Fv<version>/biome-linux-x64 -o biome
chmod +x biome
```

--------------------------------

### Invalid example 2 with fix

Source: https://v1.biomejs.dev/linter/rules/no-blank-target

The same invalid example with the suggested fix.

```jsx
<a href='http://external.link' target='_blank' rel="noreferrer·noopener">child</a>
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-guard-for-in

Configuration to enable the useGuardForIn rule.

```json
{
  "linter": {
    "rules": {
      "nursery": {
        "useGuardForIn": "error"
      }
    }
  }
}
```

--------------------------------

### Prettier Configuration

Source: https://v1.biomejs.dev/guides/migrate-eslint-prettier

An example of a Prettier configuration file.

```json
{
  "useTabs": false,
  "singleQuote": true,
  "overrides": [
    {
          "files": ["*.json"],
          "options": { "tabWidth": 2 }
      }
  ]
}
```

--------------------------------

### Lint and fix files using pnpm

Source: https://v1.biomejs.dev/guides/getting-started

Lints specified files or directories and applies safe fixes using the Biome CLI with pnpm.

```bash
pnpm biome lint --write <files>
```

--------------------------------

### Lint and fix files using yarn

Source: https://v1.biomejs.dev/guides/getting-started

Lints specified files or directories and applies safe fixes using the Biome CLI with yarn.

```bash
yarn biome lint --write <files>
```

--------------------------------

### biome init usage

Source: https://v1.biomejs.dev/reference/cli

Initializes a new Biome project by creating a configuration file with default settings.

```bash
biome init [--jsonc]
```

--------------------------------

### $schema - Local path

Source: https://v1.biomejs.dev/reference/configuration

Allows to pass a path to a JSON schema file. This example shows how to specify a relative path to the schema if @biomejs/biome is installed in node_modules.

```json
{
  "$schema": "./node_modules/@biomejs/biome/configuration_schema.json"
}
```

--------------------------------

### Search command output example

Source: https://v1.biomejs.dev/blog

Example output from the `biome search` command, showing matched lines.

```text
./benchmark/bench.js:38:3 search ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  **38 │ 	console.info(`\n⌛ repository: ${name}`);**

./packages/@biomejs/js-api/scripts/update-nightly-version.mjs:27:1 search ━━━━━━━━━━━━━━

  **27 │  console.log(`version=${version}`);**

Searched 67 files in 1034ms. Found 2 matches.
```

--------------------------------

### Configuration Example

Source: https://v1.biomejs.dev/linter/rules/use-top-level-regex

This is an example of how to configure the 'useTopLevelRegex' rule in the Biome configuration file.

```json
{
  "linter": {
    "rules": {
      "performance": {
        "useTopLevelRegex": "error"
      }
    }
  }
}
```

--------------------------------

### Invalid for loop with incorrect condition direction

Source: https://v1.biomejs.dev/linter/rules/use-valid-for-direction

This example shows an invalid for loop where the counter `i` is incremented (`i++`) but the condition requires `i` to be greater than 10, which will never be met if `i` starts at 0.

```javascript
for (var i = 0; i > 10; i++) {
}

```

--------------------------------

### biome start usage

Source: https://v1.biomejs.dev/reference/cli

Starts the Biome daemon server process.

```bash
biome start [--config-path=PATH]
```

--------------------------------

### Valid code example

Source: https://v1.biomejs.dev/linter/rules/no-empty-pattern

These code examples are valid because they create new bindings, unlike the invalid examples.

```javascript
var {a = {}} = foo;
var {a, b = {}} = foo;
var {a = []} = foo;
function foo({a = {}}) {}
function foo({a = []}) {}
var [a] = foo;
```

--------------------------------

### Ignore code example

Source: https://v1.biomejs.dev/formatter

Example:

```javascript
const expr =
  // biome-ignore format: the array should not be formatted
  [
    (2 * n) / (r - l),
    0,
    (r + l) / (r - l),
    0,
    0,
    (2 * n) / (t - b),
    (t + b) / (t - b),
    0,
    0,
    0,
    -(f + n) / (f - n),
    -(2 * f * n) / (f - n),
    0,
    0,
    -1,
    0,
  ];
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-is-array

This code snippet shows how to configure the `useIsArray` rule.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "useIsArray": "error"
      }
    }
  }
}
```

--------------------------------

### React Component Example

Source: https://v1.biomejs.dev/

A React component demonstrating formatting and basic logic.

```jsx
function HelloWorld({greeting = "hello", greeted = '"World"', silent = false, onMouseOver,}) {


  if(!greeting){return null};


      // TODO: Don't use random in render
  let num = Math.floor (Math.random() * 1E+7).toString().replace(/.d+/ig, "")


  return <div className='HelloWorld' title={`You are visitor number ${ num }`} onMouseOver={onMouseOver}>


    <strong>{ greeting.slice( 0, 1 ).toUpperCase() + greeting.slice(1).toLowerCase() }</strong>
    {greeting.endsWith(",") ? " " : <span style={{color: 'grey'}}>", "</span> }
    <em>
  { greeted }
    </em>
    { (silent)
      ? "."
      : "!"}


    </div>;
}

```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-control-characters-in-regex

This is an example of how to configure the noControlCharactersInRegex rule.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noControlCharactersInRegex": "error"
      }
    }
  }
}
```

--------------------------------

### noConstantCondition example

Source: https://v1.biomejs.dev/internals/changelog

Example of `while(true)` now allowed by noConstantCondition.

```typescript
while (true) {
  if (cond) {
    break;
  }
}

```

--------------------------------

### Custom configuration for lsp-proxy and start commands

Source: https://v1.biomejs.dev/blog/biome-wins-prettier-challenge

Pass a custom configuration to the `lsp-proxy` and `start` commands using the `--config-path` option.

```bash
biome --config-path=../path/where/config/is lsp-proxy
biome --config-path=../path/where/config/is start
```

--------------------------------

### noConsoleLog example

Source: https://v1.biomejs.dev/internals/changelog

Example of code now reported by noConsoleLog.

```typescript
globalThis.console.log("log")

```

--------------------------------

### Formatter overrides example

Source: https://v1.biomejs.dev/reference/configuration

Example demonstrating how to override formatter settings like `lineWidth` and `indentStyle` for specific file globs.

```json
{
  "formatter": {
    "lineWidth": 100
  },
  "overrides": [
    {
      "include": ["generated/**"],
      "formatter": {
        "lineWidth": 160,
        "indentStyle": "space"
      }
    }
  ]
}
```

--------------------------------

### Configuration Example

Source: https://v1.biomejs.dev/linter/rules/use-jsx-key-in-iterable

Configuration for the useJsxKeyInIterable rule.

```json
{
  "linter": {
    "rules": {
      "correctness": {
        "useJsxKeyInIterable": "error"
      }
    }
  }
}
```

--------------------------------

### Example

Source: https://v1.biomejs.dev/linter/rules/use-exhaustive-dependencies

Configuration example for hooks with stable results.

```json
{
    "//": "...",
    "options": {
        "hooks": [
            { "name": "useDispatch", "stableResult": true }
        ]
    }
}
```

--------------------------------

### Biome configuration file example

Source: https://v1.biomejs.dev/guides/configure-biome

An example Biome configuration file demonstrating the use of 'files.include' and 'files.ignore' for global file processing rules, and 'linter.ignore' for tool-specific rules.

```json
{
  "files": {
    "include": ["src/**/*.js", "test/**/*.js"],
    "ignore": ["**/*.min.js"],
  },
  "linter": {
    "ignore": ["test"]
  }
}

```

--------------------------------

### Configuration example for rules without options

Source: https://v1.biomejs.dev/internals/changelog

This example shows how to configure a rule without options, where the `options` field is no longer required.

```json
{
  "linter": {
    "rules": {
      "style": {
        "noDefaultExport": {
          "level": "off"
        }
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-exponentiation-operator

Example of how to configure the `useExponentiationOperator` rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "style": {
        "useExponentiationOperator": "error"
      }
    }
  }
}
```

--------------------------------

### New 'using' syntax

Source: https://v1.biomejs.dev/internals/changelog

Example of the new 'using' syntax.

```javascript
const using = resource.lock();
```

--------------------------------

### Example

Source: https://v1.biomejs.dev/linter/rules/use-exhaustive-dependencies

Example of using hooks with the specified configuration.

```javascript
function Foo() {
    const location = useLocation(() => {}, []);
    const query = useQuery([], () => {});
}
```

--------------------------------

### Example

Source: https://v1.biomejs.dev/linter/rules/use-exhaustive-dependencies

Configuration example for validating hook dependencies.

```json
{
    "//": "...",
    "options": {
        "hooks": [
            { "name": "useLocation", "closureIndex": 0, "dependenciesIndex": 1},
            { "name": "useQuery", "closureIndex": 1, "dependenciesIndex": 0}
        ]
    }
}
```

--------------------------------

### Configuration path flag example

Source: https://v1.biomejs.dev/internals/changelog

Example of using the `--config-path` flag to specify a configuration file.

```bash
biome format --config-path=../biome.json ./src
```

--------------------------------

### Configuration Example

Source: https://v1.biomejs.dev/linter/rules/no-useless-string-raw

Example of how to configure the noUselessStringRaw rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "nursery": {
        "noUselessStringRaw": "error"
      }
    }
  }
}
```

--------------------------------

### Invalid Fragment Example 4

Source: https://v1.biomejs.dev/linter/rules/no-useless-fragments

An example of an empty fragment.

```jsx
<></>
```

```text
code-block.jsx:1:1 lint/complexity/noUselessFragments ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━  
  
  ✖ Avoid using unnecessary Fragment.  
    
  > 1 │ <></>
   **   │ ****^****^****^****^****^**  
    2 │ 
    
  ℹ A fragment is redundant if it contains only one child, or if it is the child of a html element, and is not a keyed fragment.  
    

```

--------------------------------

### Example ESLint Configuration

Source: https://v1.biomejs.dev/blog/biome-v1-7

An example of a legacy ESLint configuration file.

```json
{
  "extends": [
    "plugin:unicorn/recommended"
  ],
  "plugins": [
    "unicorn"
  ],
  "ignore_patterns": [
    "dist/**"
  ],
  "globals": {
    "Global1": "readonly"
  },
  "rules": {
    "eqeqeq": "error"
  },
  "overrides": [
    {
      "files": [
        "tests/**"
      ],
      "rules": {
        "eqeqeq": "off"
      }
    }
  ]
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-unmatchable-anb-selector

Example of how to configure the noUnmatchableAnbSelector rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "correctness": {
        "noUnmatchableAnbSelector": "error"
      }
    }
  }
}
```

--------------------------------

### Valid trimStart

Source: https://v1.biomejs.dev/linter/rules/use-trim-start-end

Example of valid code using trimStart.

```javascript
const foo = bar.trimStart();
```

--------------------------------

### Configuration

Source: https://v1.biomejs.dev/linter/rules/no-delete

Example of how to configure the noDelete rule.

```json
{
  "linter": {
    "rules": {
      "performance": {
        "noDelete": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-unsafe-negation

Example of how to configure the noUnsafeNegation rule.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noUnsafeNegation": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-unknown-pseudo-element

Example of how to configure the noUnknownPseudoElement rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "nursery": {
        "noUnknownPseudoElement": "error"
      }
    }
  }
}
```

--------------------------------

### Invalid array example

Source: https://v1.biomejs.dev/linter/rules/no-sparse-array

An example of an invalid sparse array.

```javascript
[1,,2]
```

--------------------------------

### Valid examples

Source: https://v1.biomejs.dev/linter/rules/no-misleading-character-class

These examples show valid regular expressions.

```javascript
/^[abc]$/;
```

```javascript
/^[👍]$/u;
```

```javascript
/^["q{👶🏻}]$/v;
```

--------------------------------

### Configuration Example

Source: https://v1.biomejs.dev/linter/rules/no-irregular-whitespace

This is an example of how to configure the noIrregularWhitespace rule.

```json
{
  "linter": {
    "rules": {
      "nursery": {
        "noIrregularWhitespace": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-focused-tests

This is an example of how to configure the `noFocusedTests` rule.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noFocusedTests": "error"
      }
    }
  }
}
```

--------------------------------

### JSON parser overrides example

Source: https://v1.biomejs.dev/reference/configuration

Example demonstrating how to enable JSON parsing features like `allowComments` and `allowTrailingCommas` for files within a specific directory.

```json
{
  "linter": {
    "enabled": true,
    "rules": {
      "recommended": true
    }
  },
  "overrides": [
    {
      "include": [".vscode/**"],
      "json": {
        "parser": {
          "allowComments": true,
          "allowTrailingCommas": true
        }
      }
    }
  ]
}
```

--------------------------------

### macOS arm (M1 or newer) Binary Installation

Source: https://v1.biomejs.dev/guides/manual-installation

Downloads and makes the Biome executable for macOS arm64 architecture executable.

```bash
# macOS arm (M1 or newer)
curl -L https://github.com/biomejs/biome/releases/download/cli%2Fv<version>/biome-darwin-arm64 -o biome
chmod +x biome
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-duplicate-class-members

Example of how to configure the noDuplicateClassMembers rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noDuplicateClassMembers": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-confusing-void-type

Example of how to configure the `noConfusingVoidType` rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "suspicious": {
        "noConfusingVoidType": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-as-const-assertion

This JSON object shows how to configure the `useAsConstAssertion` rule in the Biome linter.

```json
{
  "linter": {
    "rules": {
      "style": {
        "useAsConstAssertion": "error"
      }
    }
  }
}
```

--------------------------------

### How to configure

Source: https://v1.biomejs.dev/linter/rules/use-optional-chain

Configuration for the `useOptionalChain` rule.

```json
{
  "linter": {
    "rules": {
      "complexity": {
        "useOptionalChain": "error"
      }
    }
  }
}
```

--------------------------------

### useOptionalChain example

Source: https://v1.biomejs.dev/internals/changelog

Example of correctly handling logical and chains with methods of the same name.

```typescript
tags && tags.includes('a') && tags.includes('b')
tags?.includes('a') && tags.includes('b')
```

--------------------------------

### Valid examples

Source: https://v1.biomejs.dev/linter/rules/no-async-promise-executor

Examples of valid Promise executor usage.

```javascript
new Promise((resolve, reject) => {})
new Promise((resolve, reject) => {}, async function unrelated() {})
new Foo(async (resolve, reject) => {})
new Foo((( (resolve, reject) => {} )))
```

--------------------------------

### Compact log example

Source: https://v1.biomejs.dev/internals/changelog

Example of a compact log message.

```log
2023-10-05T08:29:04.864247Z  INFO biome::worker_2 Process check:Processes linting:Pulling diagnostics: crates/biome_service/src/file_handlers/javascript.rs: Analyze file ./website/src/playground/components/Resizable.tsx path="./website/src/playground/components/Resizable.tsx" path="./website/src/playground/components/Resizable.tsx" categories=RuleCategories(LINT)
2023-10-05T08:29:04.864290Z  INFO biome::worker_7 Process check:Processes formatting: crates/biome_service/src/file_handlers/javascript.rs: Format file ./website/src/playground/components/Tabs.tsx path="./website/src/playground/components/Tabs.tsx" path="./website/src/playground/components/Tabs.tsx"
2023-10-05T08:29:04.879332Z  INFO biome::worker_2 Process check:Processes formatting:Pulling diagnostics: crates/biome_service/src/file_handlers/javascript.rs: Analyze file ./website/src/playground/components/Resizable.tsx path="./website/src/playground/components/Resizable.tsx" path="./website/src/playground/components/Resizable.tsx" categories=RuleCategories(SYNTAX)
2023-10-05T08:29:04.879383Z  INFO biome::worker_2 Process check:Processes formatting: crates/biome_service/src/file_handlers/javascript.rs: Format file ./website/src/playground/components/Resizable.tsx path="./website/src/playground/components/Resizable.tsx" path="./website/src/playground/components/Resizable.tsx"
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-while

Example of how to configure the `useWhile` rule in Biome.

```json
{
  "linter": {
    "rules": {
      "style": {
        "useWhile": "error"
      }
    }
  }
}
```

--------------------------------

### Configure formatter options

Source: https://v1.biomejs.dev/guides/configure-biome

Example demonstrating general formatter options, JavaScript-specific formatter options, and disabling the formatter for JSON.

```json
{
  "formatter": {
    "indentStyle": "space", // default is `tab`
    "lineWidth": 100 // default is `80`
  },
  "javascript": {
    "formatter": {
      "quoteStyle": "single", // default is `double`
      "lineWidth": 120 // override `formatter.lineWidth`
    }
  },
  "json": {
    "formatter": {
      "enabled": false
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-self-closing-elements

Example of how to configure the `useSelfClosingElements` rule in Biome.

```json
{
  "linter": {
    "rules": {
      "style": {
        "useSelfClosingElements": "error"
      }
    }
  }
}
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-throw-new-error

Example of how to configure the `useThrowNewError` rule in Biome.

```json
{
  "linter": {
    "rules": {
      "style": {
        "useThrowNewError": "error"
      }
    }
  }
}
```

--------------------------------

### Glob example

Source: https://v1.biomejs.dev/formatter

The command accepts a list of files and directories. If you pass a glob as a parameter, your shell will expand it. The result of the expansion depends on your shell. For example, some shells don’t support the recursive glob `**` or the alternation `{}` in the following command:

```bash
biome format ./src/**/*.test.{js,ts}
```

--------------------------------

### Valid code example 1

Source: https://v1.biomejs.dev/linter/rules/no-useless-undefined-initialization

This example shows a valid initialization of a variable.

```javascript
var a = 1;
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/use-single-var-declarator

Example of how to configure the useSingleVarDeclarator rule in biome.json.

```json
{
  "linter": {
    "rules": {
      "style": {
        "useSingleVarDeclarator": "error"
      }
    }
  }
}
```

--------------------------------

### Prettier Configuration Example

Source: https://v1.biomejs.dev/blog/biome-v1-6

An example of a Prettier configuration file that Biome can migrate.

```json
{ "useTabs": false, "semi": true, "singleQuote": true }
```

--------------------------------

### Valid example

Source: https://v1.biomejs.dev/linter/rules/use-simplified-logic-expression

This example shows a valid and simplified logical expression.

```javascript
const boolExpr3 = true;
const boolExpr4 = false;
const r5 = !(boolExpr1 && boolExpr2);
const boolExpr5 = true;
const boolExpr6 = false;
```

--------------------------------

### Configuration example

Source: https://v1.biomejs.dev/linter/rules/no-setter-return

Configuration for the noSetterReturn rule.

```json
{
  "linter": {
    "rules": {
      "correctness": {
        "noSetterReturn": "error"
      }
    }
  }
}
```
Tokens:
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