# Formatting

> Format JavaScript, TypeScript, JSON, CSS, Markdown and more with bun fmt

`bun fmt` formats JavaScript, TypeScript, JSX, JSON, CSS, Markdown, YAML, TOML and more with [oxfmt](https://oxc.rs/docs/guide/usage/formatter), a Prettier-compatible formatter.

```bash terminal icon="terminal"
bun fmt
```

With no paths, oxfmt formats the working directory. Pass files, directories or globs to format only those. A path starting with `!` excludes files.

```bash terminal icon="terminal"
bun fmt src 'test/**/*.ts' '!test/fixtures'
```

## Check formatting in CI

`--check` writes nothing and exits with code `1` when a file is not formatted. `--list-different` prints those files.

```bash terminal icon="terminal"
bun fmt --check
```

## How oxfmt is installed

oxfmt is not part of the `bun` binary. The first `bun fmt` downloads a pinned version with [`bun x`](https://bun.aphrody.com/docs/pm/bunx) and caches it. `bun fmt` uses `node_modules/.bin/oxfmt` instead when the project installs oxfmt itself.

## Changed files and workspaces

```bash terminal icon="terminal"
# files changed since a git ref, plus staged, unstaged and untracked files
bun fmt --since=main

# every workspace package, or the ones matching a filter
bun fmt --workspaces
bun fmt --filter 'packages/*'
```

## Configure

`bun fmt` reads `.oxfmtrc.json` the same way oxfmt does. See the [oxfmt configuration reference](https://oxc.rs/docs/guide/usage/formatter/config).

```json .oxfmtrc.json icon="file-json"
{
  "printWidth": 120,
  "semi": true,
  "ignorePatterns": ["dist/**"]
}
```

Project defaults go in the `[fmt]` section of [`bunfig.toml`](https://bun.aphrody.com/docs/runtime/bunfig).

```toml bunfig.toml icon="settings"
[fmt]
# oxfmt configuration file
config = ".oxfmtrc.json"
# paths formatted when none are given
paths = ["src", "test"]
# glob patterns to skip
ignore = ["dist/**"]
# more oxfmt arguments
args = []
# oxfmt version to download
version = "0.72.0"
```

## Flags

| Flag                    | Description                                         |
| ----------------------- | --------------------------------------------------- |
| `--check`               | Write nothing; exit with `1` if a file is not formatted |
| `--list-different`      | Print the files that are not formatted              |
| `--since=<ref>`         | Only files changed since a git ref                  |
| `--workspaces`          | Format every workspace package                      |
| `--filter=<pattern>`    | Format the workspace packages whose name or path matches |
| `-c`, `--config=<path>` | oxfmt configuration file                            |

Every other flag goes to oxfmt.

If `package.json` has a `fmt` script, `bun fmt` runs that script. Inside the script, `bun fmt` is the command.

To lint code, use [`bun lint`](https://bun.aphrody.com/docs/runtime/lint).