format-file

Format files based on existing formatter configs like Biome.

Table of Contents

• Introduction
• Installation
• Example
• API
  • formatFile
  • formatFiles
  • formatText

Introduction

Code and config generation is hard enough already. Some of this code should be checked into version control, and should therefore abide by the repositories code formatting rules.

format-file is a package which will return a formatted version of generated JSON, typescript, and javascript files by inferring the formatting rules at runtime.

Under the hood, it uses either the user's configured biome or prettier setup to format files on their behalf.

Installation

npm i format-file

Format-file is an ESM package. It must be imported.

Due to peer dependencies on biome + prettier, it is recommended to install at least one of them as well (or set up a similar peer dependency).

Example

// generated.ts
export    const  foo={
abc   : 123,
      efg:456  ,
} ;

// index.ts
import { formatFile, formatText } from 'format-file';

await formatFile('./generated.ts');
readFileSync('/generated.ts', 'utf8');
/**
 * export const foo = {
 *   abc: 123,
 *   efg: 456
 * };
 */

await formatText(`
{     "abc":123   ,
     "efg":
              456}
`, { ext: '.json' });
/**
 * {
 *   "abc": 123,
 *   "efg": 456
 * }
 */

Usage

File formatting is best effort and is not necessarily guaranteed to succeed. Primarily if the repo does not have biome or prettier installed.

It is recommended to create reasonable files before formatting, such as generating JSON files using JSON.stringify(content, null, 2) as a reasonable default.

Both biome and prettier have been declared as optional peerDependencies in this package. If using this library as an internal functionality, it is recommended to keep biome and prettier as optional peer dependencies to maintain your package's dependency.

API

formatFile(filePath, options?)

Formats a file in-place.

The first parameter is the file path. If the path is relative, will be resolved from working directory just like regular fs methods.

The second parameter is an optional object with a formatter property. While the default behavior is 'inherit' which will iterate over viable formatters based on support. It may be overridden with 'biome' or 'parser'.

Returns a promise which when resolved, means the file is formatted according user settings.

formatFiles(filePath[], options?)

Formats a set of files in-place.

First parameter is a list of file paths. Any paths that are relative will be resolved from working directory just like regular fs methods.

Second parameter is an optional object the same as formatFile

Returns a promise which when resolved, means the files are formatted according user settings.

formatText(content, options?)

Formats an inline text body as if it were a file.

Parameter is the raw text body.

Second parameter is options which include a ext, which defaults to .js. It also support sthe formatter option that formatFile has.

Returns a promise which resolves to a formatted version of the text.