Script to automate 90% of CommonJS -> ESM (#20016)

* Create convert-cjs-to-esm.mjs * Update convert-cjs-to-esm.mjs * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * update script * Address a goofy export * Update convert-cjs-to-esm.mjs * Fix more exports * Revert "Merge branch 'goofy-export' into cjs-esm-script" This reverts commit c23927b824916ee5bc1443849a0edc3a5765cec6, reversing changes made to 4e760d33f63838b164bc95f18447945d173cc849. * Apply suggestions from code review Co-authored-by: James M. Greene <JamesMGreene@github.com> Co-authored-by: James M. Greene <JamesMGreene@github.com>
2025-12-23 11:54:18 -05:00 · 2021-07-12 11:07:30 -07:00
parent 493b50c13c
commit fed486f7d7
1 changed files with 271 additions and 0 deletions
--- a/script/code/convert-cjs-to-esm.mjs
+++ b/script/code/convert-cjs-to-esm.mjs
@@ -0,0 +1,271 @@
+#!/usr/bin/env node
+
+/*
+
+This script does most of the work to convert our *.js files to use ESM
+instead of CommonJS.
+
+This is based on https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c
+
+This file assumes the two ESLint rules have already been installed and enforced:
+
+- https://github.com/mysticatea/eslint-plugin-node/blob/master/docs/rules/global-require.md
+- https://github.com/benmosher/eslint-plugin-import/blob/master/docs/rules/no-dynamic-require.md
+
+(for reference) https://github.com/sindresorhus/eslint-plugin-unicorn/blob/main/docs/rules/prefer-module.md
+
+*/
+
+import fs from 'fs/promises'
+import semver from 'semver'
+import walkSync from 'walk-sync'
+
+// https://stackoverflow.com/a/31102605
+function orderKeys (unordered) {
+  return Object.keys(unordered).sort().reduce(
+    (obj, key) => {
+      obj[key] = unordered[key].constructor === {}.constructor
+        ? orderKeys(unordered[key])
+        : unordered[key]
+      return obj
+    },
+    {}
+  )
+}
+
+async function readPackageFile () {
+  return JSON.parse(await fs.readFile('./package.json', 'utf8'))
+}
+
+async function writePackageFile (packageFile) {
+  return fs.writeFile('./package.json', JSON.stringify(orderKeys(packageFile), ' ', 2) + '\n')
+}
+
+async function readAllJsFiles () {
+  const paths = walkSync('./', {
+    directories: false,
+    includeBasePath: true,
+    globs: ['**/*.js'],
+    ignore: ['node_modules', 'dist']
+  })
+  return await Promise.all(
+    paths.map(
+      async path => [path, await fs.readFile(path, 'utf8')]
+    )
+  )
+}
+
+function listJsonPaths () {
+  const paths = walkSync('./', {
+    directories: false,
+    includeBasePath: true,
+    globs: ['**/*.json'],
+    ignore: ['node_modules', 'dist']
+  })
+  return paths.map(p => p.replace('.json', ''))
+}
+
+function withAllFiles(jsFiles, fn) {
+  return jsFiles.map(
+    ([path, file]) => [path, fn(path, file)]
+  )
+}
+
+async function writeAllJsFiles (jsFiles) {
+  return await Promise.all(
+    jsFiles.map(
+      async ([path, file]) => await fs.writeFile(path, file)
+    )
+  )
+}
+
+// Converts a path to an import name
+/* Example:
+  import xLunrJa from 'lunr-languages/lunr.ja'
+  xLunrJa(lunr)
+*/
+function nameImport(p2) {
+  const myString = p2.split('/').pop()
+  const string = myString.replace(/[-\.]([a-z])/g, (g) => g[1].toUpperCase())
+  return `x${string.charAt(0).toUpperCase()}${string.slice(1)}`
+}
+
+// Add "type": "module" to your package.json.
+async function addTypeModule () {
+  const packageFile = await readPackageFile()
+  packageFile.type = 'module'
+  return writePackageFile(packageFile)
+}
+
+// Replace "main": "index.js" with "exports": "./index.js" in your package.json.
+async function updateMainExport () {
+  const packageFile = await readPackageFile()
+  const main = packageFile.main
+  if (!main) return
+  delete packageFile.main
+  packageFile.exports = './' + main
+  return writePackageFile(packageFile)
+}
+
+// Update the "engines" field in package.json to Node.js 12: "node": "^12.20.0 || ^14.13.1 || >=16.0.0".
+// If 12 is already required, we will skip this change.
+async function checkEngines () {
+  const packageFile = await readPackageFile()
+  const nodeVersion = packageFile.engines.node
+  if (semver.gt(semver.minVersion(nodeVersion), '12.0.0')) return
+  packageFile.engines.node = "^12.20.0 || ^14.13.1 || >=16.0.0"
+  await writePackageFile(packageFile)
+}
+
+// Remove 'use strict'; from all JavaScript files.
+function noStrict (path, file) {
+  if (file.includes('use strict')) {
+    throw new Error(`Cannot use strict in ${path}. Please remove and run this script again.`)
+  }
+  return file
+}
+
+// Read JSON requires separately
+/*
+import { promises as fs } from 'fs'
+
+const packageJson = JSON.parse(await fs.readFile('package.json', 'utf8'))
+*/
+function noJsonReads (jsonPaths) {
+  return (path, file) => {
+    const found = [...file.matchAll(/require\('[\.\/]+(.*?)'\)/gm)]
+    if (!found) return file
+    const matchesJsonPath = found
+        .map(f => f[1])
+        .filter(f => jsonPaths.some(p => p.endsWith(f)))
+    if (matchesJsonPath.length) {
+      throw new Error(`${path} has possible JSON requires: ${matchesJsonPath}. Please fix this manually then run the script again.`)
+    }
+    return file
+  }
+}
+
+// Replace all require()/module.export with import/export.
+// Use only full relative file paths for imports: import x from '.'; → import x from './index.js';.
+// Add `.js` if starts with `./`
+// Replace `:` to as
+
+// Fix up standard const x = require('x') statements
+function updateStandardImport (path, file) {
+  return file.replaceAll(
+    /^const\s(.*?)\s*?=\s*?require\('(.*?)'\)$/gm,
+    (_, p1, p2) => {
+      // Replace `:` to as
+      p1 = p1.replace(/\s*:\s*/g, ' as ')
+      // Add `.js` if path starts with `.`
+      if (p2.startsWith('.') && !p2.endsWith('.js')) p2 = p2 + '.js'
+      return `import ${p1} from '${p2}'`
+    }
+  )
+}
+
+// Fix up inlined requires that are still "top-level"
+function updateInlineImport (path, file) {
+  return file.replaceAll(
+    /^(.*?)require\('(.*?)'\)(.*)$/gm,
+    (_, p1, p2, p3) => {
+      // Generate a new import name based on the path
+      const name = nameImport(p2)
+      // Add `.js` if starts with `.`
+      if (p2.startsWith('.') && !p2.endsWith('.js')) p2 = p2 + '.js'
+      // Fix up unused require('x') statements
+      if (!p1 && !p3) return `import '${p2}'`
+      return `import ${name} from '${p2}'\n${p1}${name}${p3}`
+    }
+  )
+}
+
+// Handle module.exports =
+function updateDefaultExport (path, file) {
+  return file.replaceAll(
+    /^module.exports\s*?=\s*?(\S.*)/gm,
+    'export default $1'
+  )
+}
+
+// Handle exports.x =
+function updateNamedExport (path, file) {
+  return file.replaceAll(
+    /^exports\.(\S+)\s*?=\s*?(\S.*)/gm,
+    'export const $1 = $2'
+  )
+}
+
+// Replace __filename and __dirname
+function updateFileAndDir (path, file) {
+  if (!file.includes('__filename') && !file.includes('__dirname')) return file
+
+  return [
+    'import { fileURLToPath } from \'node:url\'',
+    'import path from \'node:path\'',
+    file.includes('__filename') && 'const __filename = fileURLToPath(import.meta.url)',
+    file.includes('__dirname') && 'const __dirname = path.dirname(fileURLToPath(import.meta.url))',
+    file
+  ].filter(Boolean).join('\n')
+}
+
+// lodash => lodash-es
+function useEsLodash (path, file) {
+  return file.replace("'lodash'", "'lodash-es'")
+}
+
+// Pull all imports to the top of the file to avoid syntax issues
+function moveImportsToTop (path, file) {
+  if (!file.includes('import')) return file
+  const isTop = line => /^import/gm.test(line)
+  const lineEnd = /\r?\n|\r/g
+  return file.split(lineEnd).filter(isTop).join('\n') +
+         '\n' +
+         file.split(lineEnd).filter(line => !isTop(line)).join('\n')
+}
+
+// Make sure script declarations on the top of the file before imports
+function updateScriptDeclaration (path, file) {
+  if (!path.startsWith('./script')) return file
+  file = file.replace('#!/usr/bin/env node\n', '')
+  return '#!/usr/bin/env node\n' + file
+}
+
+// Check there's no `require(` ... anywhere
+function checkRequire (path, file) {
+  if (/require\s*\(/.test(file)) {
+    throw new Error(`"require(" still in ${path}`)
+  }
+  return file
+}
+
+// Check there's no `exports` ... anywhere
+function checkExports (path, file) {
+  if (file.includes('exports')) {
+    throw new Error(`"exports" still in ${path}`)
+  }
+  return file
+}
+
+async function main () {
+  await addTypeModule()
+  await updateMainExport()
+  await checkEngines()
+  const jsonPaths = listJsonPaths()
+  let jsFiles = await readAllJsFiles()
+  jsFiles = withAllFiles(jsFiles, noStrict)
+  jsFiles = withAllFiles(jsFiles, noJsonReads(jsonPaths))
+  jsFiles = withAllFiles(jsFiles, updateStandardImport)
+  jsFiles = withAllFiles(jsFiles, updateInlineImport)
+  jsFiles = withAllFiles(jsFiles, updateDefaultExport)
+  jsFiles = withAllFiles(jsFiles, updateNamedExport)
+  jsFiles = withAllFiles(jsFiles, updateFileAndDir)
+  jsFiles = withAllFiles(jsFiles, useEsLodash)
+  jsFiles = withAllFiles(jsFiles, moveImportsToTop)
+  jsFiles = withAllFiles(jsFiles, updateScriptDeclaration)
+  jsFiles = withAllFiles(jsFiles, checkRequire)
+  jsFiles = withAllFiles(jsFiles, checkExports)
+  // TBD enable await writeAllJsFiles(jsFiles)
+}
+
+main()