feat: convert to native ESM module (#1038)

BREAKING CHANGE: _lint-staged_ is now a pure ESM module, and thus
requires Node.js version `^12.20.0 || ^14.13.1 || >=16.0.0`.

To update your Node.js integration, please use:

```js
// const lintStaged = require('lint-staged')
import lintStaged from 'lint-staged'
```

.eslintrc.json

@@ -6,19 +6,35 @@
       "experimentalObjectRestSpread": true
     },
     "requireConfigFile": false,
-    "sourceType": "script"
+    "sourceType": "module"
   },
   "env": {
     "es6": true,
     "node": true
   },
-  "extends": ["eslint:recommended", "prettier"],
+  "extends": ["eslint:recommended", "plugin:import/recommended", "prettier"],
   "plugins": ["node", "import", "prettier"],
   "rules": {
+    "import/order": [
+      "error",
+      {
+        "groups": [
+          "builtin",
+          "external",
+          "internal",
+          "parent",
+          "sibling",
+          "index",
+          "object",
+          "type"
+        ],
+        "newlines-between": "always"
+      }
+    ],
     "no-console": "off",
-    "node/no-unsupported-features/node-builtins": "off",
-    "node/no-unsupported-features/es-syntax": ["error", { "version": ">=10.13.0" }],
-    "node/no-unsupported-features/es-builtins": ["error", { "version": ">=10.13.0" }],
+    "node/no-unsupported-features/es-builtins": "error",
+    "node/no-unsupported-features/es-syntax": ["error", { "ignores": ["modules"] }],
+    "node/no-unsupported-features/node-builtins": "error",
     "prettier/prettier": "error"
   }
 }

.github/workflows/codeql.yml

@@ -4,10 +4,7 @@ on:
   push:
     # Run on pushes to specific branches
     branches:
-      - master
-      - next
-      - beta
-      - alpha
+      - "*"
     # Do not run on tags
     tags-ignore:
       - "*"

.github/workflows/main.yml

@@ -60,12 +60,6 @@ jobs:
       - uses: actions/setup-node@v2
         with:
           node-version: ${{ matrix.node }}
-      # Print current Node.js version
-      - run: node --version
-      # Print current npm version
-      - run: npm --version
-      # Print current Git version
-      - run: git --version
       # Install node_modules
       - uses: actions/cache@v2
         id: cache-node_modules
@@ -76,6 +70,16 @@ jobs:
             ${{ matrix.os }}-${{ matrix.node }}-${{ hashFiles('**/package-lock.json') }}
       - if: steps.cache-node_modules.outputs.cache-hit != 'true'
         run: npm ci
+      # Print current Node.js version
+      - run: node --version
+      # Print current npm version
+      - run: npm --version
+      # Print current Git version
+      - run: git --version
+      # Print lint-staged version
+      - run: node bin/lint-staged.js --version
+      # Print lint-staged help text
+      - run: node bin/lint-staged.js --help
       # Run tests
       - run: npm test
       # Upload coverage artifact from Node.js LTS

babel.config.cjs

@@ -0,0 +1,3 @@
+module.exports = {
+  presets: [['@babel/preset-env', { modules: 'cjs', targets: { node: 'current' } }]],
+}

bin/lint-staged.js

@@ -1,36 +1,27 @@
 #!/usr/bin/env node
 
-'use strict'
+import fs from 'fs'
 
-const fs = require('fs')
+import cmdline from 'commander'
+import debug from 'debug'
+import supportsColor from 'supports-color'
+
+import lintStaged from '../lib/index.js'
+import { CONFIG_STDIN_ERROR } from '../lib/messages.js'
 
 // Force colors for packages that depend on https://www.npmjs.com/package/supports-color
-const supportsColor = require('supports-color')
 if (supportsColor.stdout) {
   process.env.FORCE_COLOR = supportsColor.stdout.level.toString()
 }
 
 // Do not terminate main Listr process on SIGINT
 process.on('SIGINT', () => {})
 
-const pkg = require('../package.json')
-require('please-upgrade-node')(
-  Object.assign({}, pkg, {
-    engines: {
-      node: '>=12.13.0', // First LTS release of 'Erbium'
-    },
-  })
-)
-
-const cmdline = require('commander')
-const debugLib = require('debug')
-const lintStaged = require('../lib')
-const { CONFIG_STDIN_ERROR } = require('../lib/messages')
-
-const debug = debugLib('lint-staged:bin')
+const packageJson = JSON.parse(fs.readFileSync('package.json'))
+const version = packageJson.version
 
 cmdline
-  .version(pkg.version)
+  .version(version)
   .option('--allow-empty', 'allow empty commits when tasks revert all staged changes', false)
   .option('-c, --config [path]', 'path to configuration file, or - to read from stdin')
   .option('-d, --debug', 'print additional debug information', false)
@@ -50,11 +41,11 @@ cmdline
   )
   .parse(process.argv)
 
+const debugLog = debug('lint-staged:bin')
 if (cmdline.debug) {
-  debugLib.enable('lint-staged*')
+  debug.enable('lint-staged*')
 }
-
-debug('Running `lint-staged@%s`', pkg.version)
+debugLog('Running `lint-staged@%s`', version)
 
 /**
  * Get the maximum length of a command-line argument string based on current platform
@@ -89,7 +80,7 @@ const options = {
   verbose: !!cmdlineOptions.verbose,
 }
 
-debug('Options parsed from command-line:', options)
+debugLog('Options parsed from command-line:', options)
 
 if (options.configPath === '-') {
   delete options.configPath

jest.config.js

@@ -0,0 +1,15 @@
+const config = {
+  collectCoverage: true,
+  collectCoverageFrom: ['lib/**/*.js'],
+  moduleDirectories: ['node_modules'],
+  setupFiles: ['./testSetup.js'],
+  snapshotSerializers: ['jest-snapshot-serializer-ansi'],
+  testEnvironment: 'node',
+  transform: {
+    '\\.[jt]sx?$': 'babel-jest',
+  },
+  /** Also transform ESM packages in `node_modules` */
+  transformIgnorePatterns: [],
+}
+
+export default config

lib/chunkFiles.js

@@ -1,16 +1,17 @@
-'use strict'
+import path from 'path'
 
-const debug = require('debug')('lint-staged:chunkFiles')
-const normalize = require('normalize-path')
-const path = require('path')
+import debug from 'debug'
+import normalize from 'normalize-path'
+
+const debugLog = debug('lint-staged:chunkFiles')
 
 /**
  * Chunk array into sub-arrays
  * @param {Array} arr
  * @param {Number} chunkCount
  * @retuns {Array<Array>}
  */
-function chunkArray(arr, chunkCount) {
+const chunkArray = (arr, chunkCount) => {
   if (chunkCount === 1) return [arr]
   const chunked = []
   let position = 0
@@ -32,21 +33,21 @@ function chunkArray(arr, chunkCount) {
  * @param {Boolean} [opts.relative] whether files are relative to `gitDir` or should be resolved as absolute
  * @returns {Array<Array<String>>}
  */
-module.exports = function chunkFiles({ files, baseDir, maxArgLength = null, relative = false }) {
+export const chunkFiles = ({ files, baseDir, maxArgLength = null, relative = false }) => {
   const normalizedFiles = files.map((file) =>
     normalize(relative || !baseDir ? file : path.resolve(baseDir, file))
   )
 
   if (!maxArgLength) {
-    debug('Skip chunking files because of undefined maxArgLength')
+    debugLog('Skip chunking files because of undefined maxArgLength')
     return [normalizedFiles] // wrap in an array to return a single chunk
   }
 
   const fileListLength = normalizedFiles.join(' ').length
-  debug(
+  debugLog(
     `Resolved an argument string length of ${fileListLength} characters from ${normalizedFiles.length} files`
   )
   const chunkCount = Math.min(Math.ceil(fileListLength / maxArgLength), normalizedFiles.length)
-  debug(`Creating ${chunkCount} chunks for maxArgLength of ${maxArgLength}`)
+  debugLog(`Creating ${chunkCount} chunks for maxArgLength of ${maxArgLength}`)
   return chunkArray(normalizedFiles, chunkCount)
 }

lib/execGit.js

@@ -1,18 +1,19 @@
-'use strict'
+import debug from 'debug'
+import execa from 'execa'
 
-const debug = require('debug')('lint-staged:git')
-const execa = require('execa')
+const debugLog = debug('lint-staged:execGit')
 
 /**
  * Explicitly never recurse commands into submodules, overriding local/global configuration.
  * @see https://git-scm.com/docs/git-config#Documentation/git-config.txt-submodulerecurse
  */
 const NO_SUBMODULE_RECURSE = ['-c', 'submodule.recurse=false']
 
-const GIT_GLOBAL_OPTIONS = [...NO_SUBMODULE_RECURSE]
+// exported for tests
+export const GIT_GLOBAL_OPTIONS = [...NO_SUBMODULE_RECURSE]
 
-module.exports = async function execGit(cmd, options = {}) {
-  debug('Running git command', cmd)
+export const execGit = async (cmd, options = {}) => {
+  debugLog('Running git command', cmd)
   try {
     const { stdout } = await execa('git', GIT_GLOBAL_OPTIONS.concat(cmd), {
       ...options,
@@ -24,6 +25,3 @@ module.exports = async function execGit(cmd, options = {}) {
     throw new Error(all)
   }
 }
-
-// exported for tests
-module.exports.GIT_GLOBAL_OPTIONS = GIT_GLOBAL_OPTIONS

lib/figures.js

@@ -1,10 +1,8 @@
-const { blue, redBright, yellow } = require('colorette')
-const { figures } = require('listr2')
+import { blue, redBright, yellow } from 'colorette'
+import { figures } from 'listr2'
 
-const { arrowRight, cross, warning } = figures
+export const info = blue(figures.arrowRight)
 
-module.exports = {
-  info: blue(arrowRight),
-  error: redBright(cross),
-  warning: yellow(warning),
-}
+export const error = redBright(figures.cross)
+
+export const warning = yellow(figures.warning)

lib/file.js

@@ -1,26 +1,22 @@
-'use strict'
+import { promises as fs } from 'fs'
 
-const debug = require('debug')('lint-staged:file')
-const fs = require('fs')
-const { promisify } = require('util')
+import debug from 'debug'
 
-const fsReadFile = promisify(fs.readFile)
-const fsUnlink = promisify(fs.unlink)
-const fsWriteFile = promisify(fs.writeFile)
+const debugLog = debug('lint-staged:file')
 
 /**
  * Read contents of a file to buffer
  * @param {String} filename
  * @param {Boolean} [ignoreENOENT=true] — Whether to throw if the file doesn't exist
  * @returns {Promise<Buffer>}
  */
-const readFile = async (filename, ignoreENOENT = true) => {
-  debug('Reading file `%s`', filename)
+export const readFile = async (filename, ignoreENOENT = true) => {
+  debugLog('Reading file `%s`', filename)
   try {
-    return await fsReadFile(filename)
+    return await fs.readFile(filename)
   } catch (error) {
     if (ignoreENOENT && error.code === 'ENOENT') {
-      debug("File `%s` doesn't exist, ignoring...", filename)
+      debugLog("File `%s` doesn't exist, ignoring...", filename)
       return null // no-op file doesn't exist
     } else {
       throw error
@@ -33,13 +29,13 @@ const readFile = async (filename, ignoreENOENT = true) => {
  * @param {String} filename
  * @param {Boolean} [ignoreENOENT=true] — Whether to throw if the file doesn't exist
  */
-const unlink = async (filename, ignoreENOENT = true) => {
-  debug('Removing file `%s`', filename)
+export const unlink = async (filename, ignoreENOENT = true) => {
+  debugLog('Removing file `%s`', filename)
   try {
-    await fsUnlink(filename)
+    await fs.unlink(filename)
   } catch (error) {
     if (ignoreENOENT && error.code === 'ENOENT') {
-      debug("File `%s` doesn't exist, ignoring...", filename)
+      debugLog("File `%s` doesn't exist, ignoring...", filename)
     } else {
       throw error
     }
@@ -51,13 +47,7 @@ const unlink = async (filename, ignoreENOENT = true) => {
  * @param {String} filename
  * @param {Buffer} buffer
  */
-const writeFile = async (filename, buffer) => {
-  debug('Writing file `%s`', filename)
-  await fsWriteFile(filename, buffer)
-}
-
-module.exports = {
-  readFile,
-  unlink,
-  writeFile,
+export const writeFile = async (filename, buffer) => {
+  debugLog('Writing file `%s`', filename)
+  await fs.writeFile(filename, buffer)
 }

lib/generateTasks.js

@@ -1,10 +1,10 @@
-'use strict'
+import path from 'path'
 
-const micromatch = require('micromatch')
-const normalize = require('normalize-path')
-const path = require('path')
+import debug from 'debug'
+import micromatch from 'micromatch'
+import normalize from 'normalize-path'
 
-const debug = require('debug')('lint-staged:gen-tasks')
+const debugLog = debug('lint-staged:generateTasks')
 
 /**
  * Generates all task commands, and filelist
@@ -16,8 +16,8 @@ const debug = require('debug')('lint-staged:gen-tasks')
  * @param {boolean} [options.files] - Staged filepaths
  * @param {boolean} [options.relative] - Whether filepaths to should be relative to gitDir
  */
-const generateTasks = ({ config, cwd = process.cwd(), gitDir, files, relative = false }) => {
-  debug('Generating linter tasks')
+export const generateTasks = ({ config, cwd = process.cwd(), gitDir, files, relative = false }) => {
+  debugLog('Generating linter tasks')
 
   const absoluteFiles = files.map((file) => normalize(path.resolve(gitDir, file)))
   const relativeFiles = absoluteFiles.map((file) => normalize(path.relative(cwd, file)))
@@ -47,10 +47,8 @@ const generateTasks = ({ config, cwd = process.cwd(), gitDir, files, relative =
     const fileList = matches.map((file) => normalize(relative ? file : path.resolve(cwd, file)))
 
     const task = { pattern, commands, fileList }
-    debug('Generated task: \n%O', task)
+    debugLog('Generated task: \n%O', task)
 
     return task
   })
 }
-
-module.exports = generateTasks