Migrate from oxfmt to bun fmt

bun fmt reads your .oxfmtrc.json and prints what oxfmt 0.72 prints. In most projects you only change the command.

Start with --doctor. It shows what Bun will do with your config, and it doesn't format or write anything.

bun fmt --doctor

Using .oxfmtrc.json (oxfmt config)

    3 files are formatted natively

Still needed:   oxfmt (the "format" script runs it)

Change the scripts.

package.json

{
  "scripts": {
    "format": "oxfmt", // [!code --]
    "format:check": "oxfmt --check", // [!code --]
    "format": "bun fmt", // [!code ++]
    "format:check": "bun fmt --check" // [!code ++]
  }
}

Flags and arguments stay the same. Change CI and Git hooks too.

If your script is called fmt, don't skip this: bun fmt runs a fmt script when package.json has one, so you'd still get oxfmt.

Check that nothing changes. With an oxfmt config, a run prints what oxfmt prints.

bun fmt --check

$ bun fmt --check
Checking formatting...

All matched files use the correct format.
Finished in 4ms on 3 files using 64 threads.

If you're on a version of oxfmt before 0.72, a few files change once, like when you upgrade oxfmt.

Run --doctor again. No script runs oxfmt anymore, so you can uninstall it.

You can remove: oxfmt
Not checked:    other tools' configs, CI files, Git hooks

bun remove oxfmt

No .oxfmtrc.json? Add one with {} in it first. Without a config file, the oxfmt dependency is how Bun knows to format like oxfmt and not like Prettier.

Bun reads everything oxfmt reads:

.oxfmtrc.json, .oxfmtrc.jsonc, and oxfmt.config.ts, with overrides and ignorePatterns
The fmt key of vite.config.ts, if you use vite-plus
Every option, including sortImports, sortPackageJson, sortTailwindcss, jsdoc, and svelte
// oxfmt-ignore and // prettier-ignore comments
Every flag of oxfmt 0.72 except --lsp and --migrate

It also follows oxfmt's defaults: lines wrap at 100 columns, every .gitignore in the repository counts, TOML files are formatted, and .prettierrc is ignored.

Still have a .prettierrc next to .oxfmtrc.json? Bun uses .oxfmtrc.json and tells you so. Delete the one you no longer use, or pick one with --config.

note: Using .oxfmtrc.json. .prettierrc is ignored. Use --config to pick it.

Keep oxfmt if your editor's oxc extension uses it. bun fmt has no language server.

Differences from oxfmt

If bun fmt and oxfmt 0.72 print different code, that's a bug. Open an issue. These differences are intentional:

The output is oxfmt 0.72's, whatever version you had installed.
No --lsp or --migrate.
Errors and warnings are worded differently.
An invalid TOML file is left alone, with a warning. oxfmt rewrites the parts it can read.
A file that isn't valid UTF-8 is still formatted, and the invalid bytes are kept. oxfmt exits with code 2.
Where oxfmt's output changes what a file means, Bun's differs. That's rare. In TOML oxfmt joins the lines of an inline table with a comment, which comments out the rest of the table. Bun keeps one entry per line. In Svelte oxfmt drops the comment in {#if a /* b */}, the space in <hr />some <b>words</b>, and an empty {:catch}, and it empties the <script> after a comment that mentions <style>. Bun keeps them.