Migrate babel-worker.cjs to ESM (#17681)

* Migrate `babel-worker.cjs` to ESM

* Will CircleCI fail?

* Revert "Will CircleCI fail?"

This reverts commit 50c39523d391fa8a06858f893f45aa094c846375.

Gulpfile.mts

@@ -34,7 +34,7 @@ import babelPluginToggleBooleanFlag from "./scripts/babel-plugin-toggle-boolean-
 // @ts-expect-error no types
 import formatCode from "./scripts/utils/formatCode.js";
 // @ts-expect-error no types
-import { log } from "./scripts/utils/logger.cjs";
+import { log } from "./scripts/utils/logger.js";
 import { commonJS } from "$repo-utils";
 
 import type { NodePath, PluginItem, types } from "@babel/core";
@@ -259,20 +259,25 @@ function createWorker(useWorker: boolean) {
     // For some reason, on CircleCI the workers hang indefinitely.
     process.env.CIRCLECI
   ) {
-    return require("./babel-worker.cjs");
+    // @ts-expect-error no types
+    return import("./babel-worker.mjs");
   }
-  const worker = new JestWorker(require.resolve("./babel-worker.cjs"), {
-    enableWorkerThreads: true,
-    numWorkers,
-    exposedMethods: ["transform"],
-  });
+  const worker = new JestWorker(
+    new URL("./babel-worker.mjs", import.meta.url),
+    {
+      enableWorkerThreads: true,
+      numWorkers,
+      exposedMethods: ["transform"],
+    }
+  );
+
   worker.getStdout().pipe(process.stdout);
   worker.getStderr().pipe(process.stderr);
   return worker;
 }
 
 async function buildBabel(useWorker: boolean, ignore: PackageInfo[] = []) {
-  const worker = createWorker(useWorker);
+  const worker = await createWorker(useWorker);
   const files = new Glob(defaultSourcesGlob, {
     ignore: ignore.map(p => `${p.src}/**`),
     posix: true,

babel-worker.mjs

@@ -1,11 +1,10 @@
 // @ts-check
 
-"use strict";
-const { transformAsync } = require("@babel/core");
-const { mkdirSync, statSync, readFileSync, writeFileSync } = require("node:fs");
-const path = require("node:path");
-const { log } = require("./scripts/utils/logger.cjs");
-const colors = require("picocolors");
+import { transformAsync } from "@babel/core";
+import { mkdirSync, statSync, readFileSync, writeFileSync } from "node:fs";
+import path from "node:path";
+import { log } from "./scripts/utils/logger.js";
+import colors from "picocolors";
 
 /** * Check if the source file needs to be compiled based on its modification time
  * compared to the destination file.
@@ -30,7 +29,7 @@ function needCompile(src, dest) {
   return srcStat.mtimeMs >= destStat.mtimeMs;
 }
 
-exports.transform = async function transform(src, dest, opts = {}) {
+export async function transform(src, dest, opts = {}) {
   mkdirSync(path.dirname(dest), { recursive: true });
   if (!needCompile(src, dest)) {
     return;
@@ -63,4 +62,4 @@ exports.transform = async function transform(src, dest, opts = {}) {
     // @ts-expect-error code must not be for our project source
     writeFileSync(dest, code, "utf8");
   }
-};
+}

scripts/utils/logger.js

@@ -4,7 +4,7 @@
  * @param {string} msg - The message to log.
  * @param  {...any} args - Additional arguments to log.
  */
-exports.log = function (msg, ...args) {
+export function log(msg, ...args) {
   const time = new Date().toLocaleTimeString("en-US", { hour12: false });
   console.log(`[${time}] ${msg}`, ...args);
-};
+}