Formatter

Biome is an opinionated formatter that has the goal to stop all ongoing debates over styles. It follows a similar philosophy to Prettier, only supporting a few options to avoid debates over styles, turning into debates over Biome options. It deliberately resists the urge to add new options to prevent bike-shed discussions in teams so they can focus on what really matters instead.

Options

Section titled Options

The language agnostic options supported by Biome are:

• indent style (default: tab): Use spaces or tabs for indention
• tab width (default: 2): The number of spaces per indention level
• line width (default: 80): The column width at which Biome wraps code

Other formatting options are available for specific languages as well. See the configuration options for details.

Use the formatter with the CLI

Section titled Use the formatter with the CLI

By default, the formatter checks the code and emit diagnostics if there are changes in formatting:

• npm
• yarn
• pnpm
• bun
• deno

	
npx @biomejs/biome format ./src

	
yarn dlx @biomejs/biome format ./src

	
pnpm dlx @biomejs/biome format ./src

	
bunx @biomejs/biome format ./src

	
deno run -A npm:@biomejs/biome format ./src

If you want to apply the new formatting, pass the --write option:

• npm
• yarn
• pnpm
• bun
• deno

	
npx @biomejs/biome format --write ./src

	
yarn dlx @biomejs/biome format --write ./src

	
pnpm dlx @biomejs/biome format --write ./src

	
bunx @biomejs/biome format --write ./src

	
deno run -A npm:@biomejs/biome format --write ./src

Use the --help flag to know what are the available options:

• npm
• yarn
• pnpm
• bun
• deno

	
npx @biomejs/biome format --help

	
yarn dlx @biomejs/biome format --help

	
pnpm dlx @biomejs/biome format --help

	
bunx @biomejs/biome format --help

	
deno run -A npm:@biomejs/biome format --help

Or check the CLI reference section.

Configuration

Section titled Configuration

You may want to configure Biome using biome.json. The following defaults are applied:

biome.json

{
  "formatter": {
    "enabled": true,
    "formatWithErrors": false,
    "indentStyle": "tab",
    "indentWidth": 2,
    "lineWidth": 80,
    "lineEnding": "lf",
    "ignore": []
  }
}

Ignoring Code

Section titled Ignoring Code

There are times when the formatted code isn’t ideal.

For these cases, you can use a format suppression comment:

example.js

// biome-ignore format: <explanation>

Example:

example.js

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,
  ];

Per language configuration

Section titled Per language configuration

Differently from other tools, Biome places options belong to a language in a different place of its configuration.

JavaScript

Section titled JavaScript

Following, the default applied to JavaScript files:

biome.json

{
  "javascript": {
    "formatter": {
      "arrowParentheses":"always",
      "jsxQuoteStyle": "double",
      "semicolons": "always",
      "trailingComma": "all",
      "quoteProperties": "asNeeded",
      "bracketSpacing": true,
      "bracketSameLine": false
    }
  }
}