Migrate to ESM only

.eslintrc

@@ -2,7 +2,7 @@
   "parser": "@babel/eslint-parser",
   "extends": ["eslint:recommended", "eslint-config-prettier"],
   "parserOptions": {
-    "ecmaVersion": 2017,
+    "ecmaVersion": "latest",
     "sourceType": "module"
   },
   "rules": {
@@ -12,7 +12,6 @@
     "linebreak-style": ["error", "unix"],
     "max-len": ["error", 110, 2],
     "new-cap": "off",
-    "no-case-declarations": "error",
     "no-cond-assign": "off",
     "no-confusing-arrow": "error",
     "no-console": "off",
@@ -28,8 +27,6 @@
     "no-underscore-dangle": "off",
     "no-unreachable": "off",
     "no-use-before-define": "off",
-    "no-var": "error",
-    "prefer-const": "error",
     "strict": "off",
     "prettier/prettier": "error"
   },

.github/workflows/ci.yml

@@ -11,11 +11,11 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest]
-        node-version: [14, 16, 18]
-        webpack-version: ['5']
+        node-version: [16, 18, 20]
+        webpack-version: ["5"]
         include:
-          - node-version: "14.15.0" # The minimum supported node version
-            webpack-version: latest
+          - node-version: "16.17.0" # The minimum supported node version
+            webpack-version: "5.80.0" # The minimum supported webpack version
             os: ubuntu-latest
     runs-on: ${{ matrix.os }}
     steps:
@@ -24,7 +24,7 @@ jobs:
         uses: actions/setup-node@v3
         with:
           node-version: ${{ matrix.node-version }}
-          cache: 'yarn'
+          cache: "yarn"
       - name: Install dependencies
         run: yarn
       - name: Install webpack ${{ matrix.webpack-version }}
@@ -47,7 +47,7 @@ jobs:
         uses: actions/setup-node@v3
         with:
           node-version: ${{ matrix.node-version }}
-          cache: 'yarn'
+          cache: "yarn"
       - name: Install dependencies
         run: yarn
       - name: Run lint and coverage tests
@@ -56,4 +56,3 @@ jobs:
         uses: codecov/codecov-action@v3
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
-

babel.config.json

@@ -1,12 +1,15 @@
 {
   "targets": {
-    "node": "14.15.0"
+    "node": "16.17.0"
   },
   "presets": [
-    ["@babel/preset-env", {
-      "loose": true,
-      "bugfixes": true,
-      "modules": false
-    }]
+    [
+      "@babel/preset-env",
+      {
+        "loose": true,
+        "bugfixes": true,
+        "modules": false
+      }
+    ]
   ]
 }

package.json

@@ -7,23 +7,27 @@
   ],
   "main": "lib/index.js",
   "engines": {
-    "node": ">= 14.15.0"
+    "node": ">=18 || ^16.17.0"
+  },
+  "type": "module",
+  "exports": {
+    ".": "./lib/index.js",
+    "./package.json": "./package.json"
   },
   "dependencies": {
     "find-cache-dir": "^4.0.0",
     "schema-utils": "^4.0.0"
   },
   "peerDependencies": {
     "@babel/core": "^7.12.0",
-    "webpack": ">=5"
+    "webpack": "^5.80.0"
   },
   "devDependencies": {
-    "@ava/babel": "^1.0.1",
     "@babel/cli": "^7.22.9",
     "@babel/core": "^7.22.9",
     "@babel/eslint-parser": "^7.22.9",
     "@babel/preset-env": "^7.22.9",
-    "ava": "^3.13.0",
+    "ava": "^5.3.1",
     "babel-plugin-react-intl": "^8.2.25",
     "c8": "^8.0.0",
     "eslint": "^8.45.0",
@@ -38,7 +42,7 @@
     "react-intl-webpack-plugin": "^0.3.0",
     "rimraf": "^5.0.1",
     "semver": "7.5.2",
-    "webpack": "^5.74.0"
+    "webpack": "^5.88.2"
   },
   "scripts": {
     "clean": "rimraf lib/",
@@ -89,12 +93,7 @@
       "test/**/*.test.js",
       "!test/fixtures/**/*",
       "!test/helpers/**/*"
-    ],
-    "babel": {
-      "compileAsTests": [
-        "test/helpers/**/*"
-      ]
-    }
+    ]
   },
   "lint-staged": {
     "scripts/*.js": [

src/Error.js

@@ -32,4 +32,4 @@ class LoaderError extends Error {
   }
 }
 
-module.exports = LoaderError;
+export default LoaderError;

src/cache.js

@@ -7,15 +7,15 @@
  * @see https://github.com/babel/babel-loader/issues/34
  * @see https://github.com/babel/babel-loader/pull/41
  */
-const os = require("os");
-const path = require("path");
-const zlib = require("zlib");
-const crypto = require("crypto");
-const { promisify } = require("util");
-const { readFile, writeFile, mkdir } = require("fs/promises");
+import os from "node:os";
+import path from "node:path";
+import zlib from "node:zlib";
+import crypto from "node:crypto";
+import { promisify } from "node:util";
+import { readFile, writeFile, mkdir } from "node:fs/promises";
 const findCacheDirP = import("find-cache-dir");
 
-const transform = require("./transform");
+import transform from "./transform.js";
 // Lazily instantiated when needed
 let defaultCacheDirectory = null;
 
@@ -162,7 +162,7 @@ const handleCache = async function (directory, params) {
  *   });
  */
 
-module.exports = async function (params) {
+export default async function cache(params) {
   let directory;
 
   if (typeof params.cacheDirectory === "string") {
@@ -178,4 +178,4 @@ module.exports = async function (params) {
   }
 
   return await handleCache(directory, params);
-};
+}

src/index.js

@@ -1,6 +1,6 @@
 let babel;
 try {
-  babel = require("@babel/core");
+  babel = await import("@babel/core");
 } catch (err) {
   if (err.code === "MODULE_NOT_FOUND") {
     err.message +=
@@ -19,23 +19,26 @@ if (/^6\./.test(babel.version)) {
   );
 }
 
+import { createRequire } from "node:module";
+const require = createRequire(import.meta.url);
+
 const { version } = require("../package.json");
-const cache = require("./cache");
-const transform = require("./transform");
-const injectCaller = require("./injectCaller");
-const schema = require("./schema");
+import cache from "./cache.js";
+import transform from "./transform.js";
+import injectCaller from "./injectCaller.js";
+const schema = require("./schema.json");
 
-const { isAbsolute } = require("path");
-const validateOptions = require("schema-utils").validate;
+import { isAbsolute } from "node:path";
+import { validate as validateOptions } from "schema-utils";
 
 function subscribe(subscriber, metadata, context) {
   if (context[subscriber]) {
     context[subscriber](metadata);
   }
 }
 
-module.exports = makeLoader();
-module.exports.custom = makeLoader;
+export default makeLoader();
+export const custom = makeLoader;
 
 function makeLoader(callback) {
   const overrides = callback ? callback(babel) : undefined;

src/injectCaller.js

@@ -1,6 +1,6 @@
-const babel = require("@babel/core");
+import babel from "@babel/core";
 
-module.exports = function injectCaller(opts, target) {
+export default function injectCaller(opts, target) {
   if (!supportsCallerOption()) return opts;
 
   return Object.assign({}, opts, {
@@ -24,7 +24,7 @@ module.exports = function injectCaller(opts, target) {
       opts.caller,
     ),
   });
-};
+}
 
 // TODO: We can remove this eventually, I'm just adding it so that people have
 // a little time to migrate to the newer RCs of @babel/core without getting

src/transform.js

@@ -1,13 +1,10 @@
-const babel = require("@babel/core");
-const { promisify } = require("util");
-const LoaderError = require("./Error");
+import { transformAsync } from "@babel/core";
+import LoaderError from "./Error.js";
 
-const transform = promisify(babel.transform);
-
-module.exports = async function (source, options) {
+export default async function (source, options) {
   let result;
   try {
-    result = await transform(source, options);
+    result = await transformAsync(source, options);
   } catch (err) {
     throw err.message && err.codeFrame ? new LoaderError(err) : err;
   }
@@ -34,6 +31,6 @@ module.exports = async function (source, options) {
     // Convert it from a Set to an Array to make it JSON-serializable.
     externalDependencies: Array.from(externalDependencies || []),
   };
-};
+}
 
-module.exports.version = babel.version;
+export { version } from "@babel/core";