frolint

IMPORTANT NOTICE: We plan to stop maintaining this package. As of v4, the frolint script supports ESLint v9, but we will not support v10 and later versions. We strongly recommend using husky and lint-staged to lint and format git-staged files during the pre-commit phase and/or in CI.

Breaking changes in v4

frolint v4 supports ESLint v9, so it uses flat config format. frolint v3 and earlier, it implicitly loads eslint-config-wantedly or eslint-config-wantedly-typescript as a base rule set, whereas v4 does not. If you want use eslint-config-wantedly or eslint-config-wantedly-typescript as a base rule set, you explicitly load them and put them into your root eslint.config.js like sample below.

import configWantedlyTs from "eslint-config-wantedly-typescript";
// Or if you use JavaScript only
// import configWantedly from "eslint-config-wantedly";

export default [
  ...configWantedlyTs,
  // ...configWantedly,
  {
    name: "Your rule name",
    plugins: {
      // Plugins you want to use...
    },
    rules: {
      // Overrides.
    },
  },
];

Overview

Install depending on your package manager:

yarn add -D frolint

npm install -D frolint

And you should use the export command if you want to use prettier configuration with your favorite editor.

yarn frolint export

Usage

You can use this package as a standalone dependency, it will use the default configurations.

If you want to amend the ESLint configuration, you must add a .eslintrc at the root directory of your project. Then to still make use of our curated defaults, start by extending our configs. For example in a typescript project:

{
  "extends": "wantedly-typescript",
  // your config..
}

Git commit hook

When you intend to commit some files including JS / TS files, the frolint reports if the code has some ESLint errors and warnings. If the code has ESLint errors, the commit is canceled. If your changes include only ESLint warnings, the commit is allowed but you should resolve the warnings as they will continue to appear.

git commit

Detected 2 errors, 0 warnings
./foo.js: 2 errors, 0 warnings found.
  ./foo.js:1:7 'foo' is assigned a value but never used. Allowed unused vars must match /^_/. (no-unused-vars)
  ./foo.js:1:13 'bar' is defined but never used. Allowed unused args must match /^_/. (no-unused-vars)
commit canceled with exit status 1. You have to fix ESLint errors.

To setup this commit hook, run the install command:

yarn exec frolint install

Prettier

Despite its name of linter, frolint also formats the code with the famous prettier tool. So applies the ESLint auto-fixable errors first, then applies the prettier formatting. We use a .prettierrc as below:

{
  "printWidth": 120,
  "useTabs": false,
  "semi": true,
  "singleQuote": false,
  "trailingComma": "es5",
  "bracketSpacing": true,
  "bracketSameLine": false,
  "endOfLine": "lf"
}

Help

If you want to know the options, frolint --help is helpful.

FROntend LINt Tool - 2.3.0

  $ frolint <command>

Where <command> is one of:

  frolint --version
    print version

  frolint [--typescript] [-b,--branch #0] [--expect-no-diff] [--expect-no-errors,--bail] [-f,--formatter #0] [--no-stage]
    apply ESLint and Prettier

  frolint export
    export config files when the files are not exist

  frolint print-config <filepath>
    Print the configuration for the given file

Around .git/hooks/pre-commit:

  frolint install
    install git pre-commit hook for frolint

  frolint uninstall
    uninstall git pre-commit hook for frolint

You can also print more details about any of these commands by calling them
after adding the `-h,--help` flag right after the command name.
Apply ESLint and Prettier

Usage:

$ frolint [--typescript] [-b,--branch #0] [--expect-no-diff] [--expect-no-errors,--bail] [-f,--formatter #0] [--no-stage]

Details:

Apply ESLint and Prettier. It infers the affected files which are changed from
base branch using git.

Options:

--typescript: Use @typescript-eslint/parser as ESLint parser

-b,--branch <branch name>: Find the changed files from the specified branch

--expect-no-diff: Fail when the changed files exist

--expect-no-errors: Fail out on the error instead of tolerating it (previously
--bail option)

-f,--formatter <format>: Print the report with specified format

--no-stage: Do not stage the files which have the changes made by ESLint and
Prettier auto fix functionality

Examples:

Default usage
  $ yarn frolint

Diff with the specified branch
  $ yarn frolint --branch master

Print report as stylish
  $ yarn frolint --formatter stylish

Use with reviewdog
  $ yarn frolint --formatter checkstyle | reviewdog -f=checkstyle -name="lint" -reporter=github-pr-review

In non git project, help option provides specific helps as below:

$ yarn frolint --help
yarn run v1.13.0
$ /Users/yamadayuki/dev/src/github.com/yamadayuki/sample/node_modules/.bin/frolint --help

frolint - FROntend LINT tool

Usage:
  frolint [flags]

Available Flags:
  -h, --help        help for frolint
  -f, --formatter   the ESLint formatter to print lint errors and warnings
  -F, --files       pass the files to analyze with ESLint

frolint as CLI

If you want to check all files in the repository, you can use the frolint as a binary.

yarn exec frolint

No errors and warnings!
✨  Done in 2.36s.

frolint export

Create the .prettierrc config file based on the default config in frolint.

Configuration

You can configure the frolint behaviour. frolint uses cosmiconfig for configuration file support. We have not tested except the package.json but you can configure via below files.

• package.json
• .frolintrc
• .frolintrc.json
• .frolintrc.yaml
• .frolintrc.yml
• .frolintrc.js
• frolint.config.js

typescript property

You can specify the typescript property as boolean (default is true). This means that frolint parses the JS / TS files using @typescript-eslint/parser. It is configured in eslint-config-wantedly-typescript. If you specify this as false, frolint uses the parser as babel-eslint (This is configured in eslint-config-wantedly).

{
  "frolint": {
    "typescript": false
  }
}

formatter property

You can specify the ESLint formatter as string (default is undefined). If you don't specify the formatter, frolint reports the ESLint issues using original formatter. If you want to using ESLint formatter (e.g. checkstyle), you can specify the formatter property.

{
  "frolint": {
    "formatter": "checkstyle"
  }
}

# Default original formatter
$ git commit
Detected 2 errors, 0 warnings
./foo.js: 2 errors, 0 warnings found.
  ./foo.js:1:7 'foo' is assigned a value but never used. Allowed unused vars must match /^_/. (no-unused-vars)
  ./foo.js:1:13 'bar' is defined but never used. Allowed unused args must match /^_/. (no-unused-vars)
commit canceled with exit status 1. You have to fix ESLint errors.

# "formatter": "checkstyle"
$ git commit
<?xml version="1.0" encoding="utf-8"?><checkstyle version="4.3"><file name="/Users/yamadayuki/dev/src/github.com/wantedly/frolint/foo.js"><error line="1" column="7" severity="error" message="&apos;foo&apos; is assigned a value but never used. Allowed unused vars must match /^_/. (no-unused-vars)" source="eslint.rules.no-unused-vars" /><error line="1" column="13" severity="error" message="&apos;bar&apos; is defined but never used. Allowed unused args must match /^_/. (no-unused-vars)" source="eslint.rules.no-unused-vars" /></file></checkstyle>
commit canceled with exit status 1. You have to fix ESLint errors.

prettier property

Now, frolint supports Prettier. So frolint command format the code automatically. If you specify the frolint.prettier.config property, you can use your .prettierrc to format the code.

{
  "frolint": {
    "prettier": {
      "config": "./.prettierrc"
    }
  }
}

Debugging

If you want to watch debug log, you can use DEBUG=frolint:* environment variable to output debugging information to the console via the debug package.

> DEBUG=frolint:* yarn frolint
...
  frolint:DefaultCommand Start stagings files +552ms
  frolint:DefaultCommand Start reporting results to console +4ms
  frolint:report Start reporting using frolint format +0ms
  frolint:report No errors and warnings +0ms
No errors and warnings!
  frolint:DefaultCommand Execution finished +1ms
  frolint:main Linting and Formatting complete +1s