Make esm support optional

 - requires loading the require hook the old way via a --require
 - we `--import` the ESM hook still but it only does ESM things
 - we don't load the ESM hook at all if its turned off

.github/workflows/test.yml

@@ -13,8 +13,8 @@ jobs:
       - uses: actions/checkout@v2
       - uses: ./.github/actions/setup-test-env
       - run: pnpm build
-      - run: pnpm zx integration-test/test.js
       - run: pnpm test
+      - run: pnpm integration-test
 
   lint:
     runs-on: ubuntu-latest

integration-test/cjs-with-esm-disabled/.swcrc

@@ -0,0 +1,15 @@
+{
+  "jsc": {
+    "parser": {
+      "syntax": "typescript",
+      "tsx": true,
+      "decorators": true,
+      "dynamicImport": true
+    },
+    "target": "esnext"
+  },
+  "module": {
+    "type": "commonjs",
+    "lazy": true
+  }
+}

integration-test/cjs-with-esm-disabled/package.json

@@ -0,0 +1,11 @@
+{
+  "name": "simple",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "type": "commonjs",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "license": "ISC"
+}

integration-test/cjs-with-esm-disabled/run.ts

@@ -0,0 +1,3 @@
+import { utility } from "./utils";
+
+console.log(utility("It worked!"));

integration-test/cjs-with-esm-disabled/test.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+set -ex
+
+$DIR/../../pkg/wds.bin.js $@ $DIR/run.ts | grep "IT WORKED"

integration-test/cjs-with-esm-disabled/utils.ts

@@ -0,0 +1 @@
+export const utility = (str: string) => str.toUpperCase();

integration-test/cjs-with-esm-disabled/wds.js

@@ -0,0 +1,3 @@
+module.exports = {
+    esm: false,
+};

package.json

@@ -33,6 +33,7 @@
     "lint:fix": "NODE_OPTIONS=\"--max-old-space-size=4096\" prettier --write --check \"src/**/*.{js,ts,tsx}\" && eslint --ext ts,tsx --fix src",
     "prerelease": "gitpkg publish",
     "test": "vitest run",
+    "integration-test": "pnpm run build && zx integration-test/test.js",
     "test:watch": "vitest"
   },
   "engines": {

src/Options.ts

@@ -11,6 +11,7 @@ export interface RunOptions {
 export interface ProjectConfig {
   ignore: string[];
   swc?: SwcConfig;
+  esm?: boolean;
   extensions: string[];
   cacheDir: string;
 }

src/Supervisor.ts

@@ -66,6 +66,7 @@ export class Supervisor extends EventEmitter {
         ...process.env,
         WDS_SOCKET_PATH: this.socketPath,
         WDS_EXTENSIONS: this.project.config.extensions.join(","),
+        WDS_ESM_ENABLED: this.project.config.esm ? "true" : "false",
       },
       stdio: stdio,
       detached: true,

src/hooks/child-process-cjs-hook.cts

@@ -15,6 +15,9 @@ if (!workerData || !(workerData as SyncWorkerData).isWDSSyncWorker) {
       }
   > = {};
 
+  // enable source maps
+  process.setSourceMapsEnabled(true);
+
   // Compile a given file by sending it into our async-to-sync wrapper worker js file
   // The leader process returns us a list of all the files it just compiled, so that we don't have to pay the IPC boundary cost for each file after this one
   // So, we keep a map of all the files it's compiled so far, and check it first.
@@ -37,7 +40,9 @@ if (!workerData || !(workerData as SyncWorkerData).isWDSSyncWorker) {
 
   // Register our compiler for typescript files.
   // We don't do the best practice of chaining module._compile calls because esbuild won't know about any of the stuff any of the other extensions might do, so running them wouldn't do anything. wds must then be the first registered extension.
-  for (const extension of process.env["WDS_EXTENSIONS"]!.split(",")) {
+  const extensions = process.env["WDS_EXTENSIONS"]!.split(",");
+  log.debug("registering cjs hook for extensions", extensions);
+  for (const extension of extensions) {
     require.extensions[extension] = (module: any, filename: string) => {
       const compiledFilename = compileOffThread(filename);
       if (typeof compiledFilename === "string") {

src/hooks/child-process-register.ts → src/hooks/child-process-esm-hook.ts

@@ -2,18 +2,16 @@
  * Entrypoint file passed as --import to all child processes started by wds
  */
 import { register } from "node:module";
+import { log } from "./utils.cjs";
 
 if (!register) {
   throw new Error(
     `This version of Node.js (${process.version}) does not support module.register(). Please upgrade to Node v18.19 or v20.6 and above.`
   );
 }
 
-// enable source maps
-process.setSourceMapsEnabled(true);
-
 // register the CJS hook to intercept require calls the old way
-import "./child-process-cjs-hook.cjs";
 
+log.debug("registering wds ESM loader");
 // register the ESM loader the new way
 register("./child-process-esm-loader.js", import.meta.url);

src/index.ts

@@ -8,7 +8,7 @@ import { fileURLToPath } from "url";
 import Watcher from "watcher";
 import yargs from "yargs";
 import { hideBin } from "yargs/helpers";
-import type { RunOptions } from "./Options.js";
+import type { ProjectConfig, RunOptions } from "./Options.js";
 import { Project } from "./Project.js";
 import { Supervisor } from "./Supervisor.js";
 import { MissingDestinationError, SwcCompiler } from "./SwcCompiler.js";
@@ -142,14 +142,28 @@ const startIPCServer = async (socketPath: string, project: Project) => {
   return server;
 };
 
-const childProcessArgs = () => {
-  return ["--import", path.join(dirname, "hooks", "child-process-register.js")];
+const childProcessArgs = (config: ProjectConfig) => {
+  const args = ["--require", path.join(dirname, "hooks", "child-process-cjs-hook.cjs")];
+  if (config.esm) {
+    args.push("--import", path.join(dirname, "hooks", "child-process-esm-hook.js"));
+  }
+  return args;
 };
 
 export const wds = async (options: RunOptions) => {
-  const workspaceRoot = findWorkspaceRoot(process.cwd()) || process.cwd();
+  let workspaceRoot: string;
+  let projectRoot: string;
   const workDir = await fs.mkdtemp(path.join(os.tmpdir(), "wds"));
-  log.debug(`starting wds for workspace root ${workspaceRoot} and workdir ${workDir}`);
+
+  const firstNonOptionArg = options.argv.find((arg) => !arg.startsWith("-"));
+  if (firstNonOptionArg && fs.existsSync(firstNonOptionArg)) {
+    const absolutePath = path.resolve(firstNonOptionArg);
+    projectRoot = findRoot(path.dirname(absolutePath));
+    workspaceRoot = findWorkspaceRoot(projectRoot) || projectRoot;
+  } else {
+    projectRoot = findRoot(process.cwd());
+    workspaceRoot = findWorkspaceRoot(process.cwd()) || process.cwd();
+  }
 
   let serverSocketPath: string;
   if (os.platform() === "win32") {
@@ -158,11 +172,13 @@ export const wds = async (options: RunOptions) => {
     serverSocketPath = path.join(workDir, "ipc.sock");
   }
 
-  const config = await projectConfig(findRoot(process.cwd()));
+  const config = await projectConfig(projectRoot);
+  log.debug(`starting wds for workspace root ${workspaceRoot} and workdir ${workDir}`, config);
+
   const compiler = await SwcCompiler.create(workspaceRoot, config.cacheDir);
   const project = new Project(workspaceRoot, config, compiler);
 
-  project.supervisor = new Supervisor([...childProcessArgs(), ...options.argv], serverSocketPath, options, project);
+  project.supervisor = new Supervisor([...childProcessArgs(config), ...options.argv], serverSocketPath, options, project);
 
   if (options.reloadOnChanges) startFilesystemWatcher(project);
   if (options.terminalCommands) startTerminalCommandListener(project);

src/utils.ts

@@ -27,6 +27,7 @@ export const projectConfig = async (root: string): Promise<ProjectConfig> => {
     ignore: [],
     extensions: [".ts", ".tsx", ".jsx"],
     cacheDir: path.join(root, "node_modules/.cache/wds"),
+    esm: true,
   };
 
   try {