oxfmt

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# Oxfmt — The Oxc Formatter

Oxfmt is a Prettier-compatible formatter for the JavaScript ecosystem. It currently passes ~95% of Prettier's JS/TS test suite. It formats JavaScript, JSX, TypeScript, TSX, JSON, JSONC, JSON5, YAML, TOML, HTML, Angular, Vue, CSS, SCSS, Less, Markdown, MDX, GraphQL, Ember, and Handlebars.

## When to use oxfmt

- After modifying code in a project that has oxfmt installed
- Setting up formatting in a new JS/TS project
- Migrating from Prettier to oxfmt
- Configuring formatting rules, editor integration, or CI checks

## Quick reference

### Installation

```bash
# Pick your package manager
npm add -D oxfmt
pnpm add -D oxfmt
yarn add -D oxfmt
bun add -D oxfmt
```

Add scripts to `package.json`:
```json
{
  "scripts": {
    "fmt": "oxfmt",
    "fmt:check": "oxfmt --check"
  }
}
```

Running `oxfmt` with no arguments formats the current directory (like `prettier --write .`).

### CLI flags

| Flag | Purpose |
|------|---------|
| `--check` | Check formatting without writing (exit 1 if unformatted) |
| `--list-different` | List files that would change |
| `--write` | Format and write in place (default) |
| `--init` | Create `.oxfmtrc.json` with defaults |
| `--migrate=prettier` | Convert `.prettierrc` to `.oxfmtrc.json` |
| `--migrate=biome` | Convert Biome config to `.oxfmtrc.json` |
| `-c PATH` | Use a specific config file |
| `--ignore-path PATH` | Custom ignore file (repeatable) |
| `--with-node-modules` | Include `node_modules/` (skipped by default) |
| `--no-error-on-unmatched-pattern` | Don't fail on unmatched globs |
| `--stdin-filepath PATH` | Format stdin, using PATH to infer parser |
| `--threads N` | Thread count (set to 1 for single core) |
| `--lsp` | Start the LSP server (used by editors) |

CLI does **not** support formatting options as flags (e.g., no `--no-semi`). Use the config file instead — this keeps formatting consistent across CLI, editors, and CI.

### Configuration

Oxfmt looks for `.oxfmtrc.json` or `.oxfmtrc.jsonc` starting from the current directory, walking up.

Generate a starter config:
```bash
oxfmt --init
```

#### Core options

```jsonc
{
  "$schema": "./node_modules/oxfmt/configuration_schema.json",
  "printWidth": 100,       // Line width limit (default: 100, Prettier default is 80)
  "tabWidth": 2,           // Spaces per indent level
  "useTabs": false,        // Tabs vs spaces
  "semi": true,            // Semicolons
  "singleQuote": false,    // Quote style
  "trailingComma": "all",  // Trailing commas in multi-line
  "insertFinalNewline": true
}
```

Note: oxfmt defaults `printWidth` to 100, while Prettier defaults to 80. If migrating, decide which you prefer.

#### Per-file overrides

```json
{
  "printWidth": 100,
  "overrides": [
    {
      "files": ["*.test.js", "*.spec.ts"],
      "options": { "printWidth": 120 }
    },
    {
      "files": ["*.json"],
      "excludeFiles": ["package.json"],
      "options": { "tabWidth": 4 }
    }
  ]
}
```

#### Built-in features

These are disabled by default but can be enabled in the config:

- **`sortImports`** — Sorts import statements
- **`sortTailwindcss`** — Sorts Tailwind CSS classes
- **`sortPackageJson`** — Sorts `package.json` fields (enabled by default)

#### Ignore patterns

Add `ignorePatterns` in the config file, or use a `.oxfmtignore` / `.prettierignore` file:
```json
{
  "ignorePatterns": ["dist/", "coverage/", "*.min.js"]
}
```

#### .editorconfig support

From delexw/claude-code-misc, MIT.

More from delexw/claude-code-misc