From 46848b9b99ab78a785dd167150d8d2761a675ff5 Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Fri, 1 Mar 2024 21:31:03 -0800
Subject: [PATCH 01/12] Support .cjs and .cts configs and add explicit checks
 and errors for ESM

---
 ...-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json |  11 ++
 packages/just-task/package.json               |   1 +
 packages/just-task/src/cli.ts                 |  65 +++++-----
 packages/just-task/src/config.ts              | 112 ++++++++++++++----
 packages/just-task/src/index.ts               |  12 +-
 5 files changed, 141 insertions(+), 60 deletions(-)
 create mode 100644 change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json

diff --git a/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json b/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json
new file mode 100644
index 00000000..ee99770d
--- /dev/null
+++ b/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "type": "minor",
+      "comment": "Support .cjs and .cts configs and add explicit checks and errors for ESM",
+      "packageName": "just-task",
+      "email": "elcraig@microsoft.com",
+      "dependentChangeType": "patch"
+    }
+  ]
+}
diff --git a/packages/just-task/package.json b/packages/just-task/package.json
index 96066e03..43bf99bc 100644
--- a/packages/just-task/package.json
+++ b/packages/just-task/package.json
@@ -34,6 +34,7 @@
     "chalk": "^4.0.0",
     "chokidar": "^3.5.2",
     "fs-extra": "^11.0.0",
+    "just-scripts-utils": "^2.0.1",
     "just-task-logger": ">=1.2.1 <2.0.0",
     "resolve": "^1.19.0",
     "undertaker": "^1.3.0",
diff --git a/packages/just-task/src/cli.ts b/packages/just-task/src/cli.ts
index f57bb56b..e60f2b03 100644
--- a/packages/just-task/src/cli.ts
+++ b/packages/just-task/src/cli.ts
@@ -39,41 +39,50 @@ function showHelp() {
   }
 }
 
-// Define a built-in option of "config" so users can specify which path to choose for configurations
-option('config', {
-  describe: 'path to a just configuration file (includes the file name, e.g. /path/to/just.config.ts)',
-});
-option('defaultConfig', {
-  describe:
-    'path to a default just configuration file that will be used when the current project does not have a just configuration file. (includes the file name, e.g. /path/to/just.config.ts)',
-});
-option('esm', {
-  describe:
-    'Configure ts-node to support imports of ESM package (changes TS module/moduleResolution settings to Node16)',
-});
+async function run() {
+  // Define a built-in option of "config" so users can specify which path to choose for configurations
+  option('config', {
+    describe: 'path to a just configuration file, e.g. ./path/to/just.config.ts',
+  });
+  option('defaultConfig', {
+    describe:
+      'path to a default just configuration file that will be used when the current project does not have a just configuration file. ' +
+      '(includes the file name, e.g. /path/to/just.config.ts)',
+  });
+  option('esm', {
+    describe:
+      'Configure ts-node to support dynamic imports of ESM package (changes TS module/moduleResolution settings to Node16). ' +
+      'Note that this does NOT enable full ES modules support.',
+  });
 
-const registry = undertaker.registry();
+  const registry = undertaker.registry();
 
-const configModule = readConfig();
+  const configModule = await readConfig();
 
-// Support named task function as exports of a config module
-if (configModule && typeof configModule === 'object') {
-  for (const taskName of Object.keys(configModule)) {
-    if (typeof configModule[taskName] == 'function') {
-      task(taskName, configModule[taskName]);
+  // Support named task function as exports of a config module
+  if (configModule && typeof configModule === 'object') {
+    for (const taskName of Object.keys(configModule)) {
+      if (typeof configModule[taskName] == 'function') {
+        task(taskName, configModule[taskName]);
+      }
     }
   }
-}
 
-const command = parseCommand();
+  const command = parseCommand();
 
-if (command) {
-  if (registry.get(command)) {
-    undertaker.series(registry.get(command))(() => undefined);
+  if (command) {
+    if (registry.get(command)) {
+      undertaker.series(registry.get(command))(() => undefined);
+    } else {
+      logger.error(`Command not defined: ${command}`);
+      process.exitCode = 1;
+    }
   } else {
-    logger.error(`Command not defined: ${command}`);
-    process.exitCode = 1;
+    showHelp();
   }
-} else {
-  showHelp();
 }
+
+run().catch(e => {
+  logger.error(e.stack || e.message || e);
+  process.exit(1);
+});
diff --git a/packages/just-task/src/config.ts b/packages/just-task/src/config.ts
index ebc02dd9..b843ddfb 100644
--- a/packages/just-task/src/config.ts
+++ b/packages/just-task/src/config.ts
@@ -4,12 +4,23 @@ import * as path from 'path';
 import { argv } from './option';
 import { resolve } from './resolve';
 import { mark, logger } from 'just-task-logger';
+import { readPackageJson } from 'just-scripts-utils';
 import { enableTypeScript } from './enableTypeScript';
 import yargsParser = require('yargs-parser');
 import { TaskFunction } from './interfaces';
 
 export function resolveConfigFile(args: yargsParser.Arguments): string | null {
-  for (const entry of [args.config, './just.config.js', './just-task.js', './just.config.ts', args.defaultConfig]) {
+  const paths = [
+    args.config,
+    './just.config.js',
+    './just-task.js',
+    './just.config.ts',
+    './just.config.cjs',
+    './just.config.cts',
+    args.defaultConfig,
+  ].filter(Boolean);
+
+  for (const entry of paths) {
     const configFile = resolve(entry);
     if (configFile) {
       return configFile;
@@ -19,39 +30,88 @@ export function resolveConfigFile(args: yargsParser.Arguments): string | null {
   return null;
 }
 
-export function readConfig(): { [key: string]: TaskFunction } | void {
-  // uses a separate instance of yargs to first parse the config (without the --help in the way) so we can parse the configFile first regardless
+export async function readConfig(): Promise<{ [key: string]: TaskFunction } | void> {
+  // uses a separate instance of yargs to first parse the config (without the --help in the way)
+  // so we can parse the configFile first regardless
   const args = argv();
   const configFile = resolveConfigFile(args);
+  const packageJson = readPackageJson(process.cwd());
+  const packageIsESM = packageJson?.type === 'module';
 
-  if (configFile && fs.existsSync(configFile)) {
-    const ext = path.extname(configFile);
-    if (ext === '.ts' || ext === '.tsx') {
-      // TODO: add option to do typechecking as well
-      enableTypeScript({ transpileOnly: true, esm: args.esm });
-    }
+  if (!configFile) {
+    const newConfigName = packageIsESM ? 'just.config.cjs' : 'just.config.js';
+    logger.error(
+      `Config file not found! Please create a file called "${newConfigName}" ` +
+        `in the root of the project next to "package.json".`,
+    );
+    process.exit(1);
+  }
 
-    try {
-      const configModule = require(configFile);
+  if (!fs.existsSync(configFile)) {
+    logger.error(`The specified config file "${configFile}" doesn't exit or couldn't be resolved.`);
+    process.exit(1);
+  }
+
+  const esmMessage = `
+Just currently does not support ESM for the config file (${configFile}).
+Ensure the file has a .cjs or .cts extension and change any top-level imports to require.
 
-      mark('registry:configModule');
+If you need to load an ES module in the config, use dynamic import() within an async function${
+    // this new mode is automatically enabled for ESM packages
+    packageIsESM ? '' : `\nand pass the --esm flag to just-scripts`
+  }.
+(Task functions may be async, and the config file may export an async function as module.exports.)
+`;
 
-      if (typeof configModule === 'function') {
-        configModule();
-      }
+  const configContents = fs.readFileSync(configFile, 'utf8');
+  const ext = path.extname(configFile).toLowerCase();
+  const isTS = /^\.[cm]?tsx?$/.test(ext);
 
-      logger.perf('registry:configModule');
+  // Check for common ESM patterns before requiring the file
+  if (
+    // Explicit ESM extension
+    ext.startsWith('.m') ||
+    // ESM package: .js or .ts files will be implicitly handled as ESM
+    (packageIsESM && !ext.startsWith('.c')) ||
+    // JS or explicit .cts file with top-level import
+    ((!isTS || ext.startsWith('.cts')) && /^import /m.test(configContents))
+  ) {
+    logger.error(esmMessage);
+    process.exit(1);
+  }
+
+  if (isTS) {
+    enableTypeScript({ transpileOnly: true, esm: args.esm || packageIsESM });
+  }
 
-      return configModule;
-    } catch (e) {
-      logger.error(`Invalid configuration file: ${configFile}`);
-      logger.error(`Error: ${e.stack || e.message || e}`);
-      process.exit(1);
+  try {
+    const configModule = require(configFile);
+
+    mark('registry:configModule');
+
+    if (typeof configModule === 'function') {
+      await configModule();
     }
-  } else {
-    logger.error(
-      `Cannot find config file "${configFile}".`,
-      `Please create a file called "just.config.js" in the root of the project next to "package.json".`,
-    );
+
+    logger.perf('registry:configModule');
+
+    return configModule;
+  } catch (e) {
+    logger.error(`Invalid configuration file: ${configFile}`);
+    logger.error(`Error: ${e.stack || e.message || e}`);
+
+    if (
+      // config or something it required was an ES module
+      // (or it used a dynamic import() in a non-ESM package without the --esm flag)
+      e.code === 'ERR_REQUIRE_ESM' ||
+      // import in a CJS module
+      (e.name === 'SyntaxError' && /\bimport\b/.test(e.message || '')) ||
+      // require in an ES module
+      (e.name === 'ReferenceError' && /\brequire\b/.test(e.message || ''))
+    ) {
+      logger.error(esmMessage);
+    }
+
+    process.exit(1);
   }
 }
diff --git a/packages/just-task/src/index.ts b/packages/just-task/src/index.ts
index 9319f38d..cd6da75a 100644
--- a/packages/just-task/src/index.ts
+++ b/packages/just-task/src/index.ts
@@ -1,10 +1,10 @@
-export * from './undertaker';
-export * from './task';
-export * from './interfaces';
+export { parallel, series, undertaker } from './undertaker';
+export { task } from './task';
+export { Task, TaskContext, TaskFunction } from './interfaces';
 export { condition } from './condition';
 export { addResolvePath, resetResolvePaths, resolve, resolveCwd } from './resolve';
 export { option, argv } from './option';
 export { clearCache } from './cache';
-export * from './logger';
-export * from './chain';
-export * from './watch';
+export { Logger, logger, mark } from './logger';
+export { chain } from './chain';
+export { watch } from './watch';

From 3d6bd9c6200f4e988573ec41fc5c71d22005f86d Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 12:30:40 -0700
Subject: [PATCH 02/12] Support ESM configs and explicit .cjs and .mjs config
 extensions

---
 .vscode/launch.json                           |  11 ++
 ...-48ef8505-5b31-4b60-bfe2-53e1433985cd.json |  11 ++
 ...-9ea30187-bf7e-4cd9-ba0a-e1af7e7b3bdc.json |  11 ++
 ...-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json |   2 +-
 ...-e400c7a0-47ba-4cf5-b712-508ad7481673.json |  11 ++
 package.json                                  |   2 +-
 .../src/tasks/webpackCliInitTask.ts           |   6 +-
 .../just-scripts/src/tasks/webpackTask.ts     |   6 +-
 packages/just-task/etc/just-task.api.md       |  11 +-
 packages/just-task/package.json               |   1 +
 .../just-task/src/__tests__/resolve.spec.ts   |  22 ++--
 packages/just-task/src/cli.ts                 |   4 +-
 packages/just-task/src/config.ts              | 121 ++++++++----------
 packages/just-task/src/enableTypeScript.ts    |  17 ++-
 packages/just-task/src/resolve.ts             |  24 ++++
 scripts/jest.config.js                        |   5 +-
 tsconfig.json                                 |   4 +-
 yarn.lock                                     |  13 +-
 18 files changed, 178 insertions(+), 104 deletions(-)
 create mode 100644 change/change-48ef8505-5b31-4b60-bfe2-53e1433985cd.json
 create mode 100644 change/change-9ea30187-bf7e-4cd9-ba0a-e1af7e7b3bdc.json
 create mode 100644 change/change-e400c7a0-47ba-4cf5-b712-508ad7481673.json

diff --git a/.vscode/launch.json b/.vscode/launch.json
index c1e3e198..b94572f5 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -37,6 +37,17 @@
       "sourceMaps": true,
       "outputCapture": "std",
       "console": "integratedTerminal"
+    },
+    {
+      "name": "Debug example-lib build",
+      "request": "launch",
+      "type": "node",
+      "runtimeExecutable": "yarn",
+      "runtimeArgs": ["run", "build"],
+      "cwd": "${workspaceFolder}/packages/example-lib",
+      "console": "integratedTerminal",
+      "outputCapture": "std",
+      "sourceMaps": true
     }
   ]
 }
diff --git a/change/change-48ef8505-5b31-4b60-bfe2-53e1433985cd.json b/change/change-48ef8505-5b31-4b60-bfe2-53e1433985cd.json
new file mode 100644
index 00000000..cb0f9059
--- /dev/null
+++ b/change/change-48ef8505-5b31-4b60-bfe2-53e1433985cd.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "type": "minor",
+      "comment": "Compile just with TS 4.7 and `module`/`moduleResolution` `\"Node16\"`",
+      "packageName": "just-scripts",
+      "email": "elcraig@microsoft.com",
+      "dependentChangeType": "patch"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/change/change-9ea30187-bf7e-4cd9-ba0a-e1af7e7b3bdc.json b/change/change-9ea30187-bf7e-4cd9-ba0a-e1af7e7b3bdc.json
new file mode 100644
index 00000000..b52245f3
--- /dev/null
+++ b/change/change-9ea30187-bf7e-4cd9-ba0a-e1af7e7b3bdc.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "type": "minor",
+      "comment": "For ts-node, use `module`/`moduleResolution` `\"Node16\"` if the local TS version supports it",
+      "packageName": "just-task",
+      "email": "elcraig@microsoft.com",
+      "dependentChangeType": "patch"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json b/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json
index ee99770d..2b7c4e18 100644
--- a/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json
+++ b/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json
@@ -2,7 +2,7 @@
   "changes": [
     {
       "type": "minor",
-      "comment": "Support .cjs and .cts configs and add explicit checks and errors for ESM",
+      "comment": "Support ESM configs and explicit .cjs and .mjs config extensions",
       "packageName": "just-task",
       "email": "elcraig@microsoft.com",
       "dependentChangeType": "patch"
diff --git a/change/change-e400c7a0-47ba-4cf5-b712-508ad7481673.json b/change/change-e400c7a0-47ba-4cf5-b712-508ad7481673.json
new file mode 100644
index 00000000..4a6da678
--- /dev/null
+++ b/change/change-e400c7a0-47ba-4cf5-b712-508ad7481673.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "type": "minor",
+      "comment": "Compile just with TS 4.7 and `module`/`moduleResolution` `\"Node16\"`",
+      "packageName": "just-task",
+      "email": "elcraig@microsoft.com",
+      "dependentChangeType": "patch"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/package.json b/package.json
index 9c498854..fcc25db8 100644
--- a/package.json
+++ b/package.json
@@ -50,7 +50,7 @@
     "prettier": "^2.8.4",
     "syncpack": "^9.0.0",
     "ts-jest": "^29.0.5",
-    "typescript": "~4.3.5",
+    "typescript": "~4.7.0",
     "vuepress": "^1.9.9",
     "vuepress-plugin-mermaidjs": "^1.9.1",
     "workspace-tools": "^0.35.2"
diff --git a/packages/just-scripts/src/tasks/webpackCliInitTask.ts b/packages/just-scripts/src/tasks/webpackCliInitTask.ts
index 7c818606..54bed257 100644
--- a/packages/just-scripts/src/tasks/webpackCliInitTask.ts
+++ b/packages/just-scripts/src/tasks/webpackCliInitTask.ts
@@ -20,13 +20,13 @@ export function webpackCliInitTask(customScaffold?: string, auto = false): TaskF
         try {
           init(null, null, null, '--auto');
         } catch (error) {
-          throw `Webpack-cli init failed with ${error.length} error(s).`;
+          throw `Webpack-cli init failed with ${(error as any).length} error(s).`;
         }
       } else {
         try {
           init();
         } catch (error) {
-          throw `Webpack-cli init failed with ${error.length} error(s).`;
+          throw `Webpack-cli init failed with ${(error as any).length} error(s).`;
         }
       }
     } else {
@@ -34,7 +34,7 @@ export function webpackCliInitTask(customScaffold?: string, auto = false): TaskF
       try {
         init(null, null, customScaffold);
       } catch (error) {
-        throw `Webpack-cli init failed with ${error.length} error(s).`;
+        throw `Webpack-cli init failed with ${(error as any).length} error(s).`;
       }
     }
   };
diff --git a/packages/just-scripts/src/tasks/webpackTask.ts b/packages/just-scripts/src/tasks/webpackTask.ts
index 8cd7ddea..2bb70cba 100644
--- a/packages/just-scripts/src/tasks/webpackTask.ts
+++ b/packages/just-scripts/src/tasks/webpackTask.ts
@@ -82,11 +82,7 @@ export function webpackTask(options?: WebpackTaskOptions): TaskFunction {
     return new Promise<void>((resolve, reject) => {
       wp(webpackConfigs, async (err: Error, stats: any) => {
         if (options && options.onCompile) {
-          const results = options.onCompile(err, stats);
-
-          if (typeof results === 'object' && results.then) {
-            await results;
-          }
+          await options.onCompile(err, stats);
         }
 
         if (options && options.outputStats) {
diff --git a/packages/just-task/etc/just-task.api.md b/packages/just-task/etc/just-task.api.md
index ea25a174..02f4f463 100644
--- a/packages/just-task/etc/just-task.api.md
+++ b/packages/just-task/etc/just-task.api.md
@@ -10,6 +10,8 @@ import { Arguments } from 'yargs-parser';
 import { Duplex } from 'stream';
 import type { FSWatcher } from 'chokidar';
 import { Logger } from 'just-task-logger';
+import { logger } from 'just-task-logger';
+import { mark } from 'just-task-logger';
 import type { Stats } from 'fs';
 import { TaskFunction as TaskFunction_2 } from 'undertaker';
 import { TaskFunctionParams } from 'undertaker';
@@ -34,6 +36,12 @@ export function clearCache(): void;
 // @public (undocumented)
 export function condition(taskName: string, conditional: () => boolean): TaskFunction_2;
 
+export { Logger }
+
+export { logger }
+
+export { mark }
+
 // Warning: (ae-forgotten-export) The symbol "OptionConfig" needs to be exported by the entry point index.d.ts
 //
 // @public (undocumented)
@@ -118,9 +126,6 @@ export function watch(globs: string | string[], optionsOrListener?: WatchListene
 // @public (undocumented)
 type WatchListener = (path: string, stats?: Stats) => void;
 
-
-export * from "just-task-logger";
-
 // (No @packageDocumentation comment for this package)
 
 ```
diff --git a/packages/just-task/package.json b/packages/just-task/package.json
index 43bf99bc..5e4ed6ff 100644
--- a/packages/just-task/package.json
+++ b/packages/just-task/package.json
@@ -34,6 +34,7 @@
     "chalk": "^4.0.0",
     "chokidar": "^3.5.2",
     "fs-extra": "^11.0.0",
+    "import-meta-resolve": "^4.0.0",
     "just-scripts-utils": "^2.0.1",
     "just-task-logger": ">=1.2.1 <2.0.0",
     "resolve": "^1.19.0",
diff --git a/packages/just-task/src/__tests__/resolve.spec.ts b/packages/just-task/src/__tests__/resolve.spec.ts
index cc8e94c3..f5ab716c 100644
--- a/packages/just-task/src/__tests__/resolve.spec.ts
+++ b/packages/just-task/src/__tests__/resolve.spec.ts
@@ -202,7 +202,7 @@ describe('resolveConfigFile', () => {
     resetResolvePaths();
   });
 
-  it('default chooses local config', () => {
+  it('default chooses local config', async () => {
     mockfs({
       config: {
         'configArgument.ts': 'formConfig',
@@ -210,11 +210,11 @@ describe('resolveConfigFile', () => {
       },
       'just.config.ts': 'localConfig',
     });
-    const resolvedConfig = config.resolveConfigFile({ config: undefined, defaultConfig: undefined } as any);
+    const resolvedConfig = await config.resolveConfigFile({});
     expect(resolvedConfig).toContain('just.config.ts');
   });
 
-  it('config argument wins over local config and defaultConfig', () => {
+  it('config argument wins over local config and defaultConfig', async () => {
     mockfs({
       config: {
         'configArgument.ts': 'formConfig',
@@ -222,14 +222,14 @@ describe('resolveConfigFile', () => {
       },
       'just.config.ts': 'localConfig',
     });
-    const resolvedConfig = config.resolveConfigFile({
+    const resolvedConfig = await config.resolveConfigFile({
       config: './config/configArgument.ts',
       defaultConfig: './config/defaultConfigArgument.ts',
-    } as any);
+    });
     expect(resolvedConfig).toContain('configArgument.ts');
   });
 
-  it('local config file wins over defaultConfig', () => {
+  it('local config file wins over defaultConfig', async () => {
     mockfs({
       config: {
         'configArgument.ts': 'formConfig',
@@ -237,24 +237,24 @@ describe('resolveConfigFile', () => {
       },
       'just.config.ts': 'localConfig',
     });
-    const resolvedConfig = config.resolveConfigFile({
+    const resolvedConfig = await config.resolveConfigFile({
       config: undefined,
       defaultConfig: './config/defaultConfigArgument.ts',
-    } as any);
+    });
     expect(resolvedConfig).toContain('just.config.ts');
   });
 
-  it('default config is used as last fallback', () => {
+  it('default config is used as last fallback', async () => {
     mockfs({
       config: {
         'configArgument.ts': 'formConfig',
         'defaultConfigArgument.ts': 'formDefaultConfig',
       },
     });
-    const resolvedConfig = config.resolveConfigFile({
+    const resolvedConfig = await config.resolveConfigFile({
       config: undefined,
       defaultConfig: './config/defaultConfigArgument.ts',
-    } as any);
+    });
     expect(resolvedConfig).toContain('defaultConfigArgument.ts');
   });
 });
diff --git a/packages/just-task/src/cli.ts b/packages/just-task/src/cli.ts
index e60f2b03..516d4062 100644
--- a/packages/just-task/src/cli.ts
+++ b/packages/just-task/src/cli.ts
@@ -50,9 +50,7 @@ async function run() {
       '(includes the file name, e.g. /path/to/just.config.ts)',
   });
   option('esm', {
-    describe:
-      'Configure ts-node to support dynamic imports of ESM package (changes TS module/moduleResolution settings to Node16). ' +
-      'Note that this does NOT enable full ES modules support.',
+    describe: 'No longer needed',
   });
 
   const registry = undertaker.registry();
diff --git a/packages/just-task/src/config.ts b/packages/just-task/src/config.ts
index b843ddfb..64eba6d0 100644
--- a/packages/just-task/src/config.ts
+++ b/packages/just-task/src/config.ts
@@ -2,28 +2,28 @@ import * as fs from 'fs';
 import * as path from 'path';
 
 import { argv } from './option';
-import { resolve } from './resolve';
+import { resolve, resolveModern } from './resolve';
 import { mark, logger } from 'just-task-logger';
-import { readPackageJson } from 'just-scripts-utils';
 import { enableTypeScript } from './enableTypeScript';
-import yargsParser = require('yargs-parser');
 import { TaskFunction } from './interfaces';
 
-export function resolveConfigFile(args: yargsParser.Arguments): string | null {
+export async function resolveConfigFile(args: { config?: string; defaultConfig?: string }): Promise<string | null> {
+  // Check for the old config paths/extensions first
   const paths = [
     args.config,
     './just.config.js',
     './just-task.js',
     './just.config.ts',
+    // Add .cjs and .mjs (.cts and .mts don't seem to work with ts-node)
     './just.config.cjs',
-    './just.config.cts',
+    './just.config.mjs',
     args.defaultConfig,
-  ].filter(Boolean);
+  ].filter((p): p is string => !!p);
 
   for (const entry of paths) {
-    const configFile = resolve(entry);
-    if (configFile) {
-      return configFile;
+    const resolved = resolve(entry) || (await resolveModern(entry));
+    if (resolved) {
+      return resolved;
     }
   }
 
@@ -33,85 +33,72 @@ export function resolveConfigFile(args: yargsParser.Arguments): string | null {
 export async function readConfig(): Promise<{ [key: string]: TaskFunction } | void> {
   // uses a separate instance of yargs to first parse the config (without the --help in the way)
   // so we can parse the configFile first regardless
-  const args = argv();
-  const configFile = resolveConfigFile(args);
-  const packageJson = readPackageJson(process.cwd());
-  const packageIsESM = packageJson?.type === 'module';
+  const args = argv() as { config?: string; defaultConfig?: string };
+  const configFile = await resolveConfigFile(args);
 
   if (!configFile) {
-    const newConfigName = packageIsESM ? 'just.config.cjs' : 'just.config.js';
     logger.error(
-      `Config file not found! Please create a file called "${newConfigName}" ` +
-        `in the root of the project next to "package.json".`,
+      `Config file not found! Please create a file called "just.config.js" ` +
+        `in the root of the package next to "package.json".`,
     );
     process.exit(1);
   }
 
   if (!fs.existsSync(configFile)) {
-    logger.error(`The specified config file "${configFile}" doesn't exit or couldn't be resolved.`);
+    logger.error(`The specified config file "${configFile}" doesn't exist or couldn't be resolved.`);
     process.exit(1);
   }
 
-  const esmMessage = `
-Just currently does not support ESM for the config file (${configFile}).
-Ensure the file has a .cjs or .cts extension and change any top-level imports to require.
-
-If you need to load an ES module in the config, use dynamic import() within an async function${
-    // this new mode is automatically enabled for ESM packages
-    packageIsESM ? '' : `\nand pass the --esm flag to just-scripts`
-  }.
-(Task functions may be async, and the config file may export an async function as module.exports.)
-`;
-
-  const configContents = fs.readFileSync(configFile, 'utf8');
   const ext = path.extname(configFile).toLowerCase();
-  const isTS = /^\.[cm]?tsx?$/.test(ext);
-
-  // Check for common ESM patterns before requiring the file
-  if (
-    // Explicit ESM extension
-    ext.startsWith('.m') ||
-    // ESM package: .js or .ts files will be implicitly handled as ESM
-    (packageIsESM && !ext.startsWith('.c')) ||
-    // JS or explicit .cts file with top-level import
-    ((!isTS || ext.startsWith('.cts')) && /^import /m.test(configContents))
-  ) {
-    logger.error(esmMessage);
-    process.exit(1);
-  }
 
-  if (isTS) {
-    enableTypeScript({ transpileOnly: true, esm: args.esm || packageIsESM });
+  if (ext === '.ts') {
+    enableTypeScript({ transpileOnly: true });
   }
 
+  let configModule = undefined;
+  let importError: unknown;
   try {
-    const configModule = require(configFile);
-
-    mark('registry:configModule');
-
-    if (typeof configModule === 'function') {
-      await configModule();
+    try {
+      if (ext !== '.cjs') {
+        // Rather than trying to infer the correct type in all cases, try import first.
+        configModule = await import(configFile);
+      }
+    } catch (e) {
+      importError = e;
     }
-
-    logger.perf('registry:configModule');
-
-    return configModule;
+    // Fall back to require
+    configModule ||= require(configFile);
   } catch (e) {
     logger.error(`Invalid configuration file: ${configFile}`);
-    logger.error(`Error: ${e.stack || e.message || e}`);
-
-    if (
-      // config or something it required was an ES module
-      // (or it used a dynamic import() in a non-ESM package without the --esm flag)
-      e.code === 'ERR_REQUIRE_ESM' ||
-      // import in a CJS module
-      (e.name === 'SyntaxError' && /\bimport\b/.test(e.message || '')) ||
-      // require in an ES module
-      (e.name === 'ReferenceError' && /\brequire\b/.test(e.message || ''))
-    ) {
-      logger.error(esmMessage);
+    if (importError) {
+      logger.error(
+        `Initially got this error trying to import() the file: ${
+          (importError as Error)?.stack || (importError as Error)?.message || importError
+        }`,
+      );
+      logger.error(
+        `Then tried to require() the file and got this error: ${(e as Error).stack || (e as Error).message || e}`,
+      );
+    } else {
+      logger.error((e as Error).stack || (e as Error).message || e);
     }
 
     process.exit(1);
   }
+
+  mark('registry:configModule');
+
+  if (typeof configModule === 'function') {
+    try {
+      await configModule();
+    } catch (e) {
+      logger.error(`Invalid configuration file: ${configFile}`);
+      logger.error(`Error running config function: ${(e as Error).stack || (e as Error).message || e}`);
+      process.exit(1);
+    }
+  }
+
+  logger.perf('registry:configModule');
+
+  return configModule;
 }
diff --git a/packages/just-task/src/enableTypeScript.ts b/packages/just-task/src/enableTypeScript.ts
index 92b6cd21..9f33e5cb 100644
--- a/packages/just-task/src/enableTypeScript.ts
+++ b/packages/just-task/src/enableTypeScript.ts
@@ -1,21 +1,32 @@
+import * as fse from 'fs-extra';
 import { resolve } from './resolve';
 import { logger } from 'just-task-logger';
 
 // eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
-export function enableTypeScript({ transpileOnly = true, esm = false }): void {
+export function enableTypeScript({ transpileOnly = true }): void {
   const tsNodeModule = resolve('ts-node');
+
   if (tsNodeModule) {
+    // Use module/moduleResolution "node16" if supported for broadest compatibility
+    let supportsNode16Setting = false;
+    const typescriptPackageJson = resolve('typescript/package.json');
+    if (typescriptPackageJson) {
+      const typescriptVersion = fse.readJsonSync(typescriptPackageJson).version as string;
+      const [major, minor] = typescriptVersion.split('.').map(Number);
+      supportsNode16Setting = major > 4 || (major === 4 && minor >= 7);
+    }
+
     const tsNode = require(tsNodeModule);
     tsNode.register({
       transpileOnly,
       skipProject: true,
       compilerOptions: {
         target: 'es2017',
-        module: esm ? 'node16' : 'commonjs',
+        module: supportsNode16Setting ? 'node16' : 'commonjs',
         strict: false,
         skipLibCheck: true,
         skipDefaultLibCheck: true,
-        moduleResolution: esm ? 'node16' : 'node',
+        moduleResolution: supportsNode16Setting ? 'node16' : 'node',
         allowJs: true,
         esModuleInterop: true,
       },
diff --git a/packages/just-task/src/resolve.ts b/packages/just-task/src/resolve.ts
index b0ee73e7..4a1bde6f 100644
--- a/packages/just-task/src/resolve.ts
+++ b/packages/just-task/src/resolve.ts
@@ -1,6 +1,8 @@
 import { sync as resolveSync } from 'resolve';
+import * as fs from 'fs';
 import * as path from 'path';
 import { argv } from './option';
+import { fileURLToPath, pathToFileURL } from 'url';
 
 export interface ResolveOptions {
   /** Directory to start resolution from. Defaults to `process.cwd()`. */
@@ -138,3 +140,25 @@ export function resolveCwd(moduleName: string, cwdOrOptions?: string | ResolveOp
   }
   return _tryResolve(moduleName, options);
 }
+
+let importMetaResolve: ((specifier: string, parent: string) => string) | undefined;
+/**
+ * Resolve a module relative to `cwd` (default `process.cwd()`) using `import-meta-resolve`.
+ * Returns the resolved module if it exists, or null otherwise.
+ */
+export async function resolveModern(moduleName: string, cwd?: string): Promise<string | null> {
+  importMetaResolve ||= (await import('import-meta-resolve')).resolve;
+  // import-meta-resolve needs a parent path ending in a filename in the correct directory
+  // (doesn't matter whether the file exists)
+  const parent = pathToFileURL(path.join(cwd || process.cwd(), 'package.json')).href;
+
+  try {
+    const resolved = fileURLToPath(importMetaResolve(moduleName, parent));
+    if (fs.existsSync(resolved)) {
+      return resolved;
+    }
+  } catch {
+    // ignore
+  }
+  return null;
+}
diff --git a/scripts/jest.config.js b/scripts/jest.config.js
index c6eb0229..17ba0cb3 100644
--- a/scripts/jest.config.js
+++ b/scripts/jest.config.js
@@ -5,7 +5,7 @@ const path = require('path');
  * Jest config for packages within the just monorepo
  * @type {import('@jest/types').Config.InitialOptions}
  */
-module.exports = {
+const config = {
   roots: ['<rootDir>/src'],
   testEnvironment: 'node',
   testMatch: ['**/?(*.)+(spec|test).[jt]s'],
@@ -16,7 +16,10 @@ module.exports = {
       {
         tsconfig: path.join(process.cwd(), 'tsconfig.json'),
         packageJson: path.join(process.cwd(), 'package.json'),
+        // badly-named option means skip type checking (it's done as part of the build)
+        isolatedModules: true,
       },
     ],
   },
 };
+module.exports = config;
diff --git a/tsconfig.json b/tsconfig.json
index d311d550..9f8553d3 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,8 +1,8 @@
 {
   "compilerOptions": {
     "target": "es2019",
-    "module": "commonjs",
-    "moduleResolution": "node",
+    "module": "Node16",
+    "moduleResolution": "Node16",
     "pretty": true,
     "declaration": true,
     "declarationMap": true,
diff --git a/yarn.lock b/yarn.lock
index f9b5dbd2..e37a4074 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6737,6 +6737,11 @@ import-local@^3.0.2:
     pkg-dir "^4.2.0"
     resolve-cwd "^3.0.0"
 
+import-meta-resolve@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/import-meta-resolve/-/import-meta-resolve-4.0.0.tgz#0b1195915689f60ab00f830af0f15cc841e8919e"
+  integrity sha512-okYUR7ZQPH+efeuMJGlq4f8ubUgO50kByRPyt/Cy1Io4PSRsPjxME+YlVaCOx+NIToW7hCsZNFJyTPFFKepRSA==
+
 imurmurhash@^0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/imurmurhash/-/imurmurhash-0.1.4.tgz#9218b9b2b928a238b13dc4fb6b6d576f231453ea"
@@ -11121,10 +11126,10 @@ typedarray@^0.0.6:
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
   integrity sha512-/aCDEGatGvZ2BIk+HmLf4ifCJFwvKFNb9/JeZPMulfgFracn9QFcAf5GO8B/mweUjSoblS5In0cWhqpfs/5PQA==
 
-typescript@~4.3.5:
-  version "4.3.5"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.3.5.tgz#4d1c37cc16e893973c45a06886b7113234f119f4"
-  integrity sha512-DqQgihaQ9cUrskJo9kIyW/+g0Vxsk8cDtZ52a3NGh0YNTfpUSArXSohyUGnvbPazEPLu398C0UxmKSOrPumUzA==
+typescript@~4.7.0:
+  version "4.7.4"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.7.4.tgz#1a88596d1cf47d59507a1bcdfb5b9dfe4d488235"
+  integrity sha512-C0WQT0gezHuw6AdY1M2jxUO83Rjf0HP7Sk1DtXj6j1EwkQNZrHAg2XPWlq62oqEhYvONq5pkC2Y9oPljWToLmQ==
 
 typescript@~5.0.4:
   version "5.0.4"

From 11199b5cf70f67264d48e1943043a4edab140dcc Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 12:35:14 -0700
Subject: [PATCH 03/12] work around crash

---
 packages/just-task/src/resolve.ts | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/packages/just-task/src/resolve.ts b/packages/just-task/src/resolve.ts
index 4a1bde6f..cd404fc7 100644
--- a/packages/just-task/src/resolve.ts
+++ b/packages/just-task/src/resolve.ts
@@ -147,6 +147,13 @@ let importMetaResolve: ((specifier: string, parent: string) => string) | undefin
  * Returns the resolved module if it exists, or null otherwise.
  */
 export async function resolveModern(moduleName: string, cwd?: string): Promise<string | null> {
+  if (process.env.JEST_WORKER_ID) {
+    // For some reason, the dynamic import below causes a segfault in Jest.
+    // This issue appears to be specific to Jest (doesn't repro when building `example-lib` in the
+    // just repo), so just fall back to the old resolver in that case.
+    return null;
+  }
+
   importMetaResolve ||= (await import('import-meta-resolve')).resolve;
   // import-meta-resolve needs a parent path ending in a filename in the correct directory
   // (doesn't matter whether the file exists)

From d12bb8124d8621c69493eba5bd473b717468882c Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 12:37:31 -0700
Subject: [PATCH 04/12] api

---
 .prettierignore                               | 1 +
 packages/just-scripts/etc/just-scripts.api.md | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/.prettierignore b/.prettierignore
index c2c0d9b1..2d09ad4d 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -10,3 +10,4 @@ temp
 LICENSE
 CHANGELOG.*
 SECURITY.md
+*.api.md
\ No newline at end of file
diff --git a/packages/just-scripts/etc/just-scripts.api.md b/packages/just-scripts/etc/just-scripts.api.md
index 01f0d4c0..d2603b4a 100644
--- a/packages/just-scripts/etc/just-scripts.api.md
+++ b/packages/just-scripts/etc/just-scripts.api.md
@@ -445,7 +445,7 @@ export interface TsLoaderOptions {
 }
 
 // @public (undocumented)
-export const tsOverlay: (overlayOptions?: TsOverlayOptions | undefined) => Partial<Configuration>;
+export const tsOverlay: (overlayOptions?: TsOverlayOptions) => Partial<Configuration>;
 
 // @public (undocumented)
 export interface TsOverlayOptions {

From 0d445940e5fc5006c70f49732a23d0fccad774eb Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 12:40:22 -0700
Subject: [PATCH 05/12] remove import-meta-resolve

---
 packages/just-task/package.json               |  1 -
 .../just-task/src/__tests__/resolve.spec.ts   | 16 ++++++++++
 packages/just-task/src/config.ts              |  4 +--
 packages/just-task/src/resolve.ts             | 31 -------------------
 yarn.lock                                     |  5 ---
 5 files changed, 18 insertions(+), 39 deletions(-)

diff --git a/packages/just-task/package.json b/packages/just-task/package.json
index 5e4ed6ff..43bf99bc 100644
--- a/packages/just-task/package.json
+++ b/packages/just-task/package.json
@@ -34,7 +34,6 @@
     "chalk": "^4.0.0",
     "chokidar": "^3.5.2",
     "fs-extra": "^11.0.0",
-    "import-meta-resolve": "^4.0.0",
     "just-scripts-utils": "^2.0.1",
     "just-task-logger": ">=1.2.1 <2.0.0",
     "resolve": "^1.19.0",
diff --git a/packages/just-task/src/__tests__/resolve.spec.ts b/packages/just-task/src/__tests__/resolve.spec.ts
index f5ab716c..7ca2db34 100644
--- a/packages/just-task/src/__tests__/resolve.spec.ts
+++ b/packages/just-task/src/__tests__/resolve.spec.ts
@@ -257,4 +257,20 @@ describe('resolveConfigFile', () => {
     });
     expect(resolvedConfig).toContain('defaultConfigArgument.ts');
   });
+
+  it('resolves .mjs config', async () => {
+    mockfs({
+      'just.config.mjs': 'localConfig',
+    });
+    const resolvedConfig = await config.resolveConfigFile({});
+    expect(resolvedConfig).toContain('just.config.mjs');
+  });
+
+  it('resolves .cjs config', async () => {
+    mockfs({
+      'just.config.cjs': 'localConfig',
+    });
+    const resolvedConfig = await config.resolveConfigFile({});
+    expect(resolvedConfig).toContain('just.config.cjs');
+  });
 });
diff --git a/packages/just-task/src/config.ts b/packages/just-task/src/config.ts
index 64eba6d0..6917581a 100644
--- a/packages/just-task/src/config.ts
+++ b/packages/just-task/src/config.ts
@@ -2,7 +2,7 @@ import * as fs from 'fs';
 import * as path from 'path';
 
 import { argv } from './option';
-import { resolve, resolveModern } from './resolve';
+import { resolve } from './resolve';
 import { mark, logger } from 'just-task-logger';
 import { enableTypeScript } from './enableTypeScript';
 import { TaskFunction } from './interfaces';
@@ -21,7 +21,7 @@ export async function resolveConfigFile(args: { config?: string; defaultConfig?:
   ].filter((p): p is string => !!p);
 
   for (const entry of paths) {
-    const resolved = resolve(entry) || (await resolveModern(entry));
+    const resolved = resolve(entry);
     if (resolved) {
       return resolved;
     }
diff --git a/packages/just-task/src/resolve.ts b/packages/just-task/src/resolve.ts
index cd404fc7..b0ee73e7 100644
--- a/packages/just-task/src/resolve.ts
+++ b/packages/just-task/src/resolve.ts
@@ -1,8 +1,6 @@
 import { sync as resolveSync } from 'resolve';
-import * as fs from 'fs';
 import * as path from 'path';
 import { argv } from './option';
-import { fileURLToPath, pathToFileURL } from 'url';
 
 export interface ResolveOptions {
   /** Directory to start resolution from. Defaults to `process.cwd()`. */
@@ -140,32 +138,3 @@ export function resolveCwd(moduleName: string, cwdOrOptions?: string | ResolveOp
   }
   return _tryResolve(moduleName, options);
 }
-
-let importMetaResolve: ((specifier: string, parent: string) => string) | undefined;
-/**
- * Resolve a module relative to `cwd` (default `process.cwd()`) using `import-meta-resolve`.
- * Returns the resolved module if it exists, or null otherwise.
- */
-export async function resolveModern(moduleName: string, cwd?: string): Promise<string | null> {
-  if (process.env.JEST_WORKER_ID) {
-    // For some reason, the dynamic import below causes a segfault in Jest.
-    // This issue appears to be specific to Jest (doesn't repro when building `example-lib` in the
-    // just repo), so just fall back to the old resolver in that case.
-    return null;
-  }
-
-  importMetaResolve ||= (await import('import-meta-resolve')).resolve;
-  // import-meta-resolve needs a parent path ending in a filename in the correct directory
-  // (doesn't matter whether the file exists)
-  const parent = pathToFileURL(path.join(cwd || process.cwd(), 'package.json')).href;
-
-  try {
-    const resolved = fileURLToPath(importMetaResolve(moduleName, parent));
-    if (fs.existsSync(resolved)) {
-      return resolved;
-    }
-  } catch {
-    // ignore
-  }
-  return null;
-}
diff --git a/yarn.lock b/yarn.lock
index e37a4074..8c10544b 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6737,11 +6737,6 @@ import-local@^3.0.2:
     pkg-dir "^4.2.0"
     resolve-cwd "^3.0.0"
 
-import-meta-resolve@^4.0.0:
-  version "4.0.0"
-  resolved "https://registry.yarnpkg.com/import-meta-resolve/-/import-meta-resolve-4.0.0.tgz#0b1195915689f60ab00f830af0f15cc841e8919e"
-  integrity sha512-okYUR7ZQPH+efeuMJGlq4f8ubUgO50kByRPyt/Cy1Io4PSRsPjxME+YlVaCOx+NIToW7hCsZNFJyTPFFKepRSA==
-
 imurmurhash@^0.1.4:
   version "0.1.4"
   resolved "https://registry.yarnpkg.com/imurmurhash/-/imurmurhash-0.1.4.tgz#9218b9b2b928a238b13dc4fb6b6d576f231453ea"

From a1d5a47cc670edf2827798752e8c6ffed6bc0967 Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 13:09:53 -0700
Subject: [PATCH 06/12] remove unnecessary check

---
 packages/just-task/src/config.ts | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/packages/just-task/src/config.ts b/packages/just-task/src/config.ts
index 6917581a..fcc216f6 100644
--- a/packages/just-task/src/config.ts
+++ b/packages/just-task/src/config.ts
@@ -1,6 +1,4 @@
-import * as fs from 'fs';
 import * as path from 'path';
-
 import { argv } from './option';
 import { resolve } from './resolve';
 import { mark, logger } from 'just-task-logger';
@@ -44,11 +42,6 @@ export async function readConfig(): Promise<{ [key: string]: TaskFunction } | vo
     process.exit(1);
   }
 
-  if (!fs.existsSync(configFile)) {
-    logger.error(`The specified config file "${configFile}" doesn't exist or couldn't be resolved.`);
-    process.exit(1);
-  }
-
   const ext = path.extname(configFile).toLowerCase();
 
   if (ext === '.ts') {

From cbf0a24049e2422ee2789744c25a0ac94093a120 Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 16:43:30 -0700
Subject: [PATCH 07/12] update messages

---
 packages/just-task/src/config.ts | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/packages/just-task/src/config.ts b/packages/just-task/src/config.ts
index fcc216f6..3c6bcf6f 100644
--- a/packages/just-task/src/config.ts
+++ b/packages/just-task/src/config.ts
@@ -35,10 +35,7 @@ export async function readConfig(): Promise<{ [key: string]: TaskFunction } | vo
   const configFile = await resolveConfigFile(args);
 
   if (!configFile) {
-    logger.error(
-      `Config file not found! Please create a file called "just.config.js" ` +
-        `in the root of the package next to "package.json".`,
-    );
+    logger.error('Config file not found. Please create a file "just.config.js" at the package root.');
     process.exit(1);
   }
 
@@ -65,12 +62,12 @@ export async function readConfig(): Promise<{ [key: string]: TaskFunction } | vo
     logger.error(`Invalid configuration file: ${configFile}`);
     if (importError) {
       logger.error(
-        `Initially got this error trying to import() the file: ${
+        `Initially got this error trying to import() the file:\n${
           (importError as Error)?.stack || (importError as Error)?.message || importError
         }`,
       );
       logger.error(
-        `Then tried to require() the file and got this error: ${(e as Error).stack || (e as Error).message || e}`,
+        `Then tried to require() the file and got this error:\n${(e as Error).stack || (e as Error).message || e}`,
       );
     } else {
       logger.error((e as Error).stack || (e as Error).message || e);

From 132a2683b458e55ad9fa29082c473540a625f1b8 Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 21:01:48 -0700
Subject: [PATCH 08/12] detect esm or cjs

---
 ...-0c7dafd4-b632-47f2-bacf-b22077ce3c51.json | 11 +++
 ...-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json |  2 +-
 packages/example-lib-esm-ts/README.md         |  3 +
 packages/example-lib-esm-ts/just.config.cts   |  7 ++
 packages/example-lib-esm-ts/package.json      | 14 ++++
 packages/example-lib-esm-ts/src/index.ts      |  1 +
 .../example-lib-esm-ts/tasks/customTask.ts    |  7 ++
 packages/example-lib-esm-ts/tsconfig.json     | 15 ++++
 packages/example-lib-esm/README.md            |  3 +
 packages/example-lib-esm/just.config.js       |  7 ++
 packages/example-lib-esm/package.json         | 14 ++++
 packages/example-lib-esm/src/index.ts         |  1 +
 packages/example-lib-esm/tasks/customTask.js  |  7 ++
 packages/example-lib-esm/tsconfig.json        | 15 ++++
 packages/example-lib/package.json             |  7 --
 .../just-scripts/src/tasks/nodeExecTask.ts    | 24 +++---
 .../src/typescript/getTsNodeEnv.ts            | 12 ++-
 packages/just-task/src/config.ts              | 59 +++++++-------
 packages/just-task/src/enableTypeScript.ts    | 77 ++++++++++---------
 yarn.lock                                     | 74 ++++++++++++++++++
 20 files changed, 271 insertions(+), 89 deletions(-)
 create mode 100644 change/change-0c7dafd4-b632-47f2-bacf-b22077ce3c51.json
 create mode 100644 packages/example-lib-esm-ts/README.md
 create mode 100644 packages/example-lib-esm-ts/just.config.cts
 create mode 100644 packages/example-lib-esm-ts/package.json
 create mode 100644 packages/example-lib-esm-ts/src/index.ts
 create mode 100644 packages/example-lib-esm-ts/tasks/customTask.ts
 create mode 100644 packages/example-lib-esm-ts/tsconfig.json
 create mode 100644 packages/example-lib-esm/README.md
 create mode 100644 packages/example-lib-esm/just.config.js
 create mode 100644 packages/example-lib-esm/package.json
 create mode 100644 packages/example-lib-esm/src/index.ts
 create mode 100644 packages/example-lib-esm/tasks/customTask.js
 create mode 100644 packages/example-lib-esm/tsconfig.json

diff --git a/change/change-0c7dafd4-b632-47f2-bacf-b22077ce3c51.json b/change/change-0c7dafd4-b632-47f2-bacf-b22077ce3c51.json
new file mode 100644
index 00000000..928c2f17
--- /dev/null
+++ b/change/change-0c7dafd4-b632-47f2-bacf-b22077ce3c51.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "type": "minor",
+      "comment": "`nodeExecTask`: add `enableTypeScript: esm` setting to run the task in `ts-node` with ESM support",
+      "packageName": "just-scripts",
+      "email": "elcraig@microsoft.com",
+      "dependentChangeType": "patch"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json b/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json
index 2b7c4e18..9c67c9d8 100644
--- a/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json
+++ b/change/change-9eb2d5fb-3a3f-4714-8fd7-5bac2166d20d.json
@@ -2,7 +2,7 @@
   "changes": [
     {
       "type": "minor",
-      "comment": "Support ESM configs and explicit .cjs and .mjs config extensions",
+      "comment": "Partial support for ESM packages: load `just.config.js` as ESM if package has `type: \"module\"`, and support explicit `.cjs`, `.mjs`, and `.cts` extensions. (`.ts` configs in packages with `type: \"module\"` are not supported due to limitations with `ts-node` `register()`.)",
       "packageName": "just-task",
       "email": "elcraig@microsoft.com",
       "dependentChangeType": "patch"
diff --git a/packages/example-lib-esm-ts/README.md b/packages/example-lib-esm-ts/README.md
new file mode 100644
index 00000000..4942bcb3
--- /dev/null
+++ b/packages/example-lib-esm-ts/README.md
@@ -0,0 +1,3 @@
+This package has `"type": "module"` in its `package.json`. If the just config was `just.config.ts`, this would be implicitly considered as ESM, and loading TS files as ESM isn't supported with `ts-node` `register()` (it must be configured with a `--loader` option when the Node process is created). So the package has to use `just.config.cts` instead.
+
+The just config also defines a `nodeExecTask` which must be handled as ESM. The custom task file can be a normal `.ts` which is treated as ESM because `enableTypeScript: 'esm'` is set, and the task is run in a separate Node process where the `--loader` can be used.
diff --git a/packages/example-lib-esm-ts/just.config.cts b/packages/example-lib-esm-ts/just.config.cts
new file mode 100644
index 00000000..c60b428a
--- /dev/null
+++ b/packages/example-lib-esm-ts/just.config.cts
@@ -0,0 +1,7 @@
+import { nodeExecTask, tscTask, task, parallel } from 'just-scripts';
+
+task('typescript', tscTask({}));
+
+task('customNodeTask', nodeExecTask({ enableTypeScript: 'esm', args: ['./tasks/customTask.ts'] }));
+
+task('build', parallel('customNodeTask', 'typescript'));
diff --git a/packages/example-lib-esm-ts/package.json b/packages/example-lib-esm-ts/package.json
new file mode 100644
index 00000000..7d763baa
--- /dev/null
+++ b/packages/example-lib-esm-ts/package.json
@@ -0,0 +1,14 @@
+{
+  "name": "example-lib-esm-ts",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "build": "just-scripts build"
+  },
+  "license": "MIT",
+  "devDependencies": {
+    "just-scripts": ">=2.2.3 <3.0.0",
+    "ts-node": "^10.0.0"
+  }
+}
diff --git a/packages/example-lib-esm-ts/src/index.ts b/packages/example-lib-esm-ts/src/index.ts
new file mode 100644
index 00000000..ef74d34b
--- /dev/null
+++ b/packages/example-lib-esm-ts/src/index.ts
@@ -0,0 +1 @@
+const a = 5;
diff --git a/packages/example-lib-esm-ts/tasks/customTask.ts b/packages/example-lib-esm-ts/tasks/customTask.ts
new file mode 100644
index 00000000..39731f3b
--- /dev/null
+++ b/packages/example-lib-esm-ts/tasks/customTask.ts
@@ -0,0 +1,7 @@
+import * as path from 'path';
+import * as fs from 'fs';
+import { fileURLToPath } from 'url';
+
+const dirname = path.dirname(fileURLToPath(import.meta.url));
+
+export const packageJson = fs.readFileSync(path.resolve(dirname, '../package.json'), 'utf-8');
diff --git a/packages/example-lib-esm-ts/tsconfig.json b/packages/example-lib-esm-ts/tsconfig.json
new file mode 100644
index 00000000..6ce85e60
--- /dev/null
+++ b/packages/example-lib-esm-ts/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "declaration": true,
+    "declarationMap": true,
+    "outDir": "lib",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "types": []
+  },
+  "include": ["src"]
+}
diff --git a/packages/example-lib-esm/README.md b/packages/example-lib-esm/README.md
new file mode 100644
index 00000000..5c7889bb
--- /dev/null
+++ b/packages/example-lib-esm/README.md
@@ -0,0 +1,3 @@
+This package has `"type": "module"` in its `package.json`, so its `just.config.js` must be loaded as ESM.
+
+The just config also defines a `nodeExecTask` which must be handled as ESM.
diff --git a/packages/example-lib-esm/just.config.js b/packages/example-lib-esm/just.config.js
new file mode 100644
index 00000000..d174515a
--- /dev/null
+++ b/packages/example-lib-esm/just.config.js
@@ -0,0 +1,7 @@
+import { nodeExecTask, tscTask, task, parallel } from 'just-scripts';
+
+task('typescript', tscTask({}));
+
+task('customNodeTask', nodeExecTask({ args: ['./tasks/customTask.js'] }));
+
+task('build', parallel('customNodeTask', 'typescript'));
diff --git a/packages/example-lib-esm/package.json b/packages/example-lib-esm/package.json
new file mode 100644
index 00000000..13f72fe4
--- /dev/null
+++ b/packages/example-lib-esm/package.json
@@ -0,0 +1,14 @@
+{
+  "name": "example-lib-esm",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "build": "just-scripts build"
+  },
+  "license": "MIT",
+  "devDependencies": {
+    "just-scripts": ">=2.2.3 <3.0.0",
+    "ts-node": "^9.1.1"
+  }
+}
diff --git a/packages/example-lib-esm/src/index.ts b/packages/example-lib-esm/src/index.ts
new file mode 100644
index 00000000..ef74d34b
--- /dev/null
+++ b/packages/example-lib-esm/src/index.ts
@@ -0,0 +1 @@
+const a = 5;
diff --git a/packages/example-lib-esm/tasks/customTask.js b/packages/example-lib-esm/tasks/customTask.js
new file mode 100644
index 00000000..39731f3b
--- /dev/null
+++ b/packages/example-lib-esm/tasks/customTask.js
@@ -0,0 +1,7 @@
+import * as path from 'path';
+import * as fs from 'fs';
+import { fileURLToPath } from 'url';
+
+const dirname = path.dirname(fileURLToPath(import.meta.url));
+
+export const packageJson = fs.readFileSync(path.resolve(dirname, '../package.json'), 'utf-8');
diff --git a/packages/example-lib-esm/tsconfig.json b/packages/example-lib-esm/tsconfig.json
new file mode 100644
index 00000000..6ce85e60
--- /dev/null
+++ b/packages/example-lib-esm/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "declaration": true,
+    "declarationMap": true,
+    "outDir": "lib",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "types": []
+  },
+  "include": ["src"]
+}
diff --git a/packages/example-lib/package.json b/packages/example-lib/package.json
index 4cd11e88..a8865d7c 100644
--- a/packages/example-lib/package.json
+++ b/packages/example-lib/package.json
@@ -2,17 +2,10 @@
   "name": "example-lib",
   "private": true,
   "version": "1.0.0",
-  "description": "",
-  "main": "index.js",
   "scripts": {
     "build": "just-scripts build"
   },
-  "keywords": [],
-  "author": "",
   "license": "MIT",
-  "engines": {
-    "node": ">=14"
-  },
   "devDependencies": {
     "just-scripts": ">=2.2.3 <3.0.0",
     "ts-node": "^9.1.1"
diff --git a/packages/just-scripts/src/tasks/nodeExecTask.ts b/packages/just-scripts/src/tasks/nodeExecTask.ts
index 21fbe3ac..0f3a44d2 100644
--- a/packages/just-scripts/src/tasks/nodeExecTask.ts
+++ b/packages/just-scripts/src/tasks/nodeExecTask.ts
@@ -17,9 +17,10 @@ export interface NodeExecTaskOptions {
   env?: NodeJS.ProcessEnv;
 
   /**
-   * Should this nodeExec task be using something like ts-node to execute the binary
+   * Whether this nodeExec task should use ts-node to execute the binary.
+   * If set to `esm`, it will use `ts-node/esm` instead of `ts-node/register`.
    */
-  enableTypeScript?: boolean;
+  enableTypeScript?: boolean | 'esm';
 
   /**
    * The tsconfig file to pass to ts-node for Typescript config
@@ -40,21 +41,22 @@ export interface NodeExecTaskOptions {
 export function nodeExecTask(options: NodeExecTaskOptions): TaskFunction {
   return function () {
     const { spawnOptions, enableTypeScript, tsconfig, transpileOnly } = options;
+    const args = [...(options.args || [])];
+    const env = { ...options.env };
 
-    const tsNodeRegister = resolveCwd('ts-node/register');
+    const esm = enableTypeScript === 'esm';
+    const tsNodeHelper = resolveCwd(esm ? 'ts-node/esm.mjs' : 'ts-node/register');
     const nodeExecPath = process.execPath;
 
-    if (enableTypeScript && tsNodeRegister) {
-      options.args = options.args || [];
-      options.args.unshift(tsNodeRegister);
-      options.args.unshift('-r');
+    if (enableTypeScript && tsNodeHelper) {
+      args.unshift(esm ? '--loader' : '-r', tsNodeHelper);
+      Object.assign(env, getTsNodeEnv(tsconfig, transpileOnly, esm));
 
-      options.env = { ...options.env, ...getTsNodeEnv(tsconfig, transpileOnly) };
-      logger.info('Executing [TS]: ' + [nodeExecPath, ...(options.args || [])].join(' '));
+      logger.info('Executing [TS]: ' + [nodeExecPath, ...args].join(' '));
     } else {
-      logger.info('Executing: ' + [nodeExecPath, ...(options.args || [])].join(' '));
+      logger.info('Executing: ' + [nodeExecPath, ...args].join(' '));
     }
 
-    return spawn(nodeExecPath, options.args, { stdio: 'inherit', env: options.env, ...spawnOptions });
+    return spawn(nodeExecPath, args, { stdio: 'inherit', env, ...spawnOptions });
   };
 }
diff --git a/packages/just-scripts/src/typescript/getTsNodeEnv.ts b/packages/just-scripts/src/typescript/getTsNodeEnv.ts
index 4861dfa0..daee4671 100644
--- a/packages/just-scripts/src/typescript/getTsNodeEnv.ts
+++ b/packages/just-scripts/src/typescript/getTsNodeEnv.ts
@@ -1,13 +1,21 @@
 import { logger } from 'just-task';
 
-export function getTsNodeEnv(tsconfig?: string, transpileOnly?: boolean): { [key: string]: string | undefined } {
+export function getTsNodeEnv(
+  tsconfig?: string,
+  transpileOnly?: boolean,
+  esm?: boolean,
+): { [key: string]: string | undefined } {
   const env: { [key: string]: string | undefined } = {};
 
   if (tsconfig) {
     logger.info(`[TS] Using ${tsconfig}`);
     env.TS_NODE_PROJECT = tsconfig;
   } else {
-    const compilerOptions = JSON.stringify({ module: 'commonjs', target: 'es2017', moduleResolution: 'node' });
+    const compilerOptions = JSON.stringify({
+      target: 'es2017',
+      moduleResolution: esm ? 'NodeNext' : 'node',
+      module: esm ? 'NodeNext' : 'commonjs',
+    });
     logger.info(`[TS] Using these compilerOptions: ${compilerOptions}`);
     env.TS_NODE_COMPILER_OPTIONS = compilerOptions;
   }
diff --git a/packages/just-task/src/config.ts b/packages/just-task/src/config.ts
index 3c6bcf6f..be1c8c93 100644
--- a/packages/just-task/src/config.ts
+++ b/packages/just-task/src/config.ts
@@ -4,6 +4,7 @@ import { resolve } from './resolve';
 import { mark, logger } from 'just-task-logger';
 import { enableTypeScript } from './enableTypeScript';
 import { TaskFunction } from './interfaces';
+import { readPackageJson } from 'just-scripts-utils';
 
 export async function resolveConfigFile(args: { config?: string; defaultConfig?: string }): Promise<string | null> {
   // Check for the old config paths/extensions first
@@ -11,15 +12,12 @@ export async function resolveConfigFile(args: { config?: string; defaultConfig?:
     args.config,
     './just.config.js',
     './just-task.js',
-    './just.config.ts',
-    // Add .cjs and .mjs (.cts and .mts don't seem to work with ts-node)
-    './just.config.cjs',
-    './just.config.mjs',
+    ...['.ts', '.cts', '.mts', '.cjs', '.mjs'].map(ext => `./just.config${ext}`),
     args.defaultConfig,
-  ].filter((p): p is string => !!p);
+  ];
 
   for (const entry of paths) {
-    const resolved = resolve(entry);
+    const resolved = entry && resolve(entry);
     if (resolved) {
       return resolved;
     }
@@ -39,40 +37,37 @@ export async function readConfig(): Promise<{ [key: string]: TaskFunction } | vo
     process.exit(1);
   }
 
+  const packageJson = readPackageJson(process.cwd());
+  const packageIsESM = packageJson?.type === 'module';
+
   const ext = path.extname(configFile).toLowerCase();
 
-  if (ext === '.ts') {
-    enableTypeScript({ transpileOnly: true });
+  if (ext === '.mts' || (packageIsESM && ext === '.ts')) {
+    // We can't support these with ts-node because we're calling register() rather than creating
+    // a child process with the custom --loader, and it appears that it's not possible to change
+    // the loader (needed for ESM) after the fact. The same limitation applies for tsx.
+    // https://typestrong.org/ts-node/docs/imports/#native-ecmascript-modules
+    logger.error('Just does not currently support ESM TypeScript configuration files. Please use a .cts file.');
+    process.exit(1);
+  }
+
+  if (/^\.[cm]?ts$/.test(ext)) {
+    const tsSuccess = enableTypeScript({ transpileOnly: true, configFile });
+    if (!tsSuccess) {
+      process.exit(1); // enableTypeScript will log the error
+    }
   }
 
   let configModule = undefined;
-  let importError: unknown;
   try {
-    try {
-      if (ext !== '.cjs') {
-        // Rather than trying to infer the correct type in all cases, try import first.
-        configModule = await import(configFile);
-      }
-    } catch (e) {
-      importError = e;
-    }
-    // Fall back to require
-    configModule ||= require(configFile);
-  } catch (e) {
-    logger.error(`Invalid configuration file: ${configFile}`);
-    if (importError) {
-      logger.error(
-        `Initially got this error trying to import() the file:\n${
-          (importError as Error)?.stack || (importError as Error)?.message || importError
-        }`,
-      );
-      logger.error(
-        `Then tried to require() the file and got this error:\n${(e as Error).stack || (e as Error).message || e}`,
-      );
+    if (ext.startsWith('.m') || (packageIsESM && !ext.startsWith('.c'))) {
+      configModule = await import(configFile);
     } else {
-      logger.error((e as Error).stack || (e as Error).message || e);
+      configModule = require(configFile);
     }
-
+  } catch (e) {
+    logger.error(`Error loading configuration file: ${configFile}`);
+    logger.error((e as Error).stack || (e as Error).message || e);
     process.exit(1);
   }
 
diff --git a/packages/just-task/src/enableTypeScript.ts b/packages/just-task/src/enableTypeScript.ts
index 9f33e5cb..d723b2f6 100644
--- a/packages/just-task/src/enableTypeScript.ts
+++ b/packages/just-task/src/enableTypeScript.ts
@@ -1,46 +1,51 @@
 import * as fse from 'fs-extra';
+import * as path from 'path';
 import { resolve } from './resolve';
 import { logger } from 'just-task-logger';
 
-// eslint-disable-next-line @typescript-eslint/explicit-module-boundary-types
-export function enableTypeScript({ transpileOnly = true }): void {
+/**
+ * Enable typescript support with ts-node.
+ * Returns true if successful.
+ */
+export function enableTypeScript(params: { transpileOnly?: boolean; configFile?: string }): boolean {
+  const { transpileOnly = true, configFile = '' } = params;
   const tsNodeModule = resolve('ts-node');
 
-  if (tsNodeModule) {
-    // Use module/moduleResolution "node16" if supported for broadest compatibility
-    let supportsNode16Setting = false;
-    const typescriptPackageJson = resolve('typescript/package.json');
-    if (typescriptPackageJson) {
-      const typescriptVersion = fse.readJsonSync(typescriptPackageJson).version as string;
-      const [major, minor] = typescriptVersion.split('.').map(Number);
-      supportsNode16Setting = major > 4 || (major === 4 && minor >= 7);
-    }
-
-    const tsNode = require(tsNodeModule);
-    tsNode.register({
-      transpileOnly,
-      skipProject: true,
-      compilerOptions: {
-        target: 'es2017',
-        module: supportsNode16Setting ? 'node16' : 'commonjs',
-        strict: false,
-        skipLibCheck: true,
-        skipDefaultLibCheck: true,
-        moduleResolution: supportsNode16Setting ? 'node16' : 'node',
-        allowJs: true,
-        esModuleInterop: true,
-      },
-      files: ['just.config.ts'],
-    });
-  } else {
-    logger.error(`In order to use TypeScript with just.config.ts, you need to install "ts-node" module:
-
-  npm install -D ts-node
-
-or
+  if (!tsNodeModule) {
+    logger.error(`In order to use TypeScript with just.config.ts, you need to install the "ts-node" package.`);
+    return false;
+  }
 
-  yarn add -D ts-node
+  // Use module/moduleResolution "node16" if supported for broadest compatibility
+  let supportsNode16Setting = false;
+  const typescriptPackageJson = resolve('typescript/package.json');
+  if (typescriptPackageJson) {
+    const typescriptVersion = fse.readJsonSync(typescriptPackageJson).version as string;
+    const [major, minor] = typescriptVersion.split('.').map(Number);
+    supportsNode16Setting = major > 4 || (major === 4 && minor >= 7);
+  }
 
-`);
+  const tsNode = require(tsNodeModule) as typeof import('ts-node');
+  const tsNodeMajor = Number(String(tsNode.VERSION || '0').split('.')[0]);
+  const ext = path.extname(configFile);
+  if (tsNodeMajor < 10 && ext !== '.ts') {
+    logger.error(`ts-node >= 10 is required for ${ext} extension support.`);
+    return false;
   }
+
+  tsNode.register({
+    transpileOnly,
+    skipProject: true,
+    compilerOptions: {
+      target: 'es2017',
+      module: supportsNode16Setting ? 'node16' : 'commonjs',
+      strict: false,
+      skipLibCheck: true,
+      skipDefaultLibCheck: true,
+      moduleResolution: supportsNode16Setting ? 'node16' : 'node',
+      allowJs: true,
+      esModuleInterop: true,
+    },
+  });
+  return true;
 }
diff --git a/yarn.lock b/yarn.lock
index 8c10544b..96d6fdd9 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1008,6 +1008,13 @@
   resolved "https://registry.yarnpkg.com/@braintree/sanitize-url/-/sanitize-url-3.1.0.tgz#8ff71d51053cd5ee4981e5a501d80a536244f7fd"
   integrity sha512-GcIY79elgB+azP74j8vqkiXz8xLFfIzbQJdlwOPisgbKT00tviJQuEghOXSMVxJ00HoYJbGswr4kcllUc4xCcg==
 
+"@cspotcode/source-map-support@^0.8.0":
+  version "0.8.1"
+  resolved "https://registry.yarnpkg.com/@cspotcode/source-map-support/-/source-map-support-0.8.1.tgz#00629c35a688e05a88b1cda684fb9d5e73f000a1"
+  integrity sha512-IchNf6dN4tHoMFIn/7OE8LWZ19Y6q/67Bmf6vnGREv8RSbBVb9LPJxEcnwrcwX6ixSvaiGoomAUvu4YSxXrVgw==
+  dependencies:
+    "@jridgewell/trace-mapping" "0.3.9"
+
 "@eslint-community/eslint-utils@^4.2.0":
   version "4.4.0"
   resolved "https://registry.yarnpkg.com/@eslint-community/eslint-utils/-/eslint-utils-4.4.0.tgz#a23514e8fb9af1269d5f7788aa556798d61c6b59"
@@ -1276,6 +1283,11 @@
     "@jridgewell/sourcemap-codec" "^1.4.10"
     "@jridgewell/trace-mapping" "^0.3.9"
 
+"@jridgewell/resolve-uri@^3.0.3":
+  version "3.1.2"
+  resolved "https://registry.yarnpkg.com/@jridgewell/resolve-uri/-/resolve-uri-3.1.2.tgz#7a0ee601f60f99a20c7c7c5ff0c80388c1189bd6"
+  integrity sha512-bRISgCIjP20/tbWSPWMEi54QVPRZExkuD9lJL+UIxUKtwVJA8wW1Trb1jMs1RFXo1CBTNZ/5hpC9QvmKWdopKw==
+
 "@jridgewell/resolve-uri@^3.1.0":
   version "3.1.1"
   resolved "https://registry.yarnpkg.com/@jridgewell/resolve-uri/-/resolve-uri-3.1.1.tgz#c08679063f279615a3326583ba3a90d1d82cc721"
@@ -1291,6 +1303,14 @@
   resolved "https://registry.yarnpkg.com/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.4.15.tgz#d7c6e6755c78567a951e04ab52ef0fd26de59f32"
   integrity sha512-eF2rxCRulEKXHTRiDrDy6erMYWqNw4LPdQ8UQA4huuxaQsVeRPFl2oM8oDGxMFhJUWZf9McpLtJasDDZb/Bpeg==
 
+"@jridgewell/trace-mapping@0.3.9":
+  version "0.3.9"
+  resolved "https://registry.yarnpkg.com/@jridgewell/trace-mapping/-/trace-mapping-0.3.9.tgz#6534fd5933a53ba7cbf3a17615e273a0d1273ff9"
+  integrity sha512-3Belt6tdc8bPgAtbcmdtNJlirVoTmEb5e2gC94PnkwEW9jI6CAHUeoG85tjWP5WquqfavoMtMwiG4P926ZKKuQ==
+  dependencies:
+    "@jridgewell/resolve-uri" "^3.0.3"
+    "@jridgewell/sourcemap-codec" "^1.4.10"
+
 "@jridgewell/trace-mapping@^0.3.12", "@jridgewell/trace-mapping@^0.3.17", "@jridgewell/trace-mapping@^0.3.18", "@jridgewell/trace-mapping@^0.3.9":
   version "0.3.19"
   resolved "https://registry.yarnpkg.com/@jridgewell/trace-mapping/-/trace-mapping-0.3.19.tgz#f8a3249862f91be48d3127c3cfe992f79b4b8811"
@@ -1444,6 +1464,26 @@
   dependencies:
     defer-to-connect "^1.0.1"
 
+"@tsconfig/node10@^1.0.7":
+  version "1.0.9"
+  resolved "https://registry.yarnpkg.com/@tsconfig/node10/-/node10-1.0.9.tgz#df4907fc07a886922637b15e02d4cebc4c0021b2"
+  integrity sha512-jNsYVVxU8v5g43Erja32laIDHXeoNvFEpX33OK4d6hljo3jDhCBDhx5dhCCTMWUojscpAagGiRkBKxpdl9fxqA==
+
+"@tsconfig/node12@^1.0.7":
+  version "1.0.11"
+  resolved "https://registry.yarnpkg.com/@tsconfig/node12/-/node12-1.0.11.tgz#ee3def1f27d9ed66dac6e46a295cffb0152e058d"
+  integrity sha512-cqefuRsh12pWyGsIoBKJA9luFu3mRxCA+ORZvA4ktLSzIuCUtWVxGIuXigEwO5/ywWFMZ2QEGKWvkZG1zDMTag==
+
+"@tsconfig/node14@^1.0.0":
+  version "1.0.3"
+  resolved "https://registry.yarnpkg.com/@tsconfig/node14/-/node14-1.0.3.tgz#e4386316284f00b98435bf40f72f75a09dabf6c1"
+  integrity sha512-ysT8mhdixWK6Hw3i1V2AeRqZ5WfXg1G43mqoYlM2nc6388Fq5jcXyr5mRsqViLx/GJYdoL0bfXD8nmF+Zn/Iow==
+
+"@tsconfig/node16@^1.0.2":
+  version "1.0.4"
+  resolved "https://registry.yarnpkg.com/@tsconfig/node16/-/node16-1.0.4.tgz#0b92dcc0cc1c81f6f306a381f28e31b1a56536e9"
+  integrity sha512-vxhUy4J8lyeyinH7Azl1pdd43GJhZH/tP2weN8TntQblOY+A0XbT8DJk1/oCPuOOyg/Ja757rG0CgHcWC8OfMA==
+
 "@types/argparse@1.0.38":
   version "1.0.38"
   resolved "https://registry.yarnpkg.com/@types/argparse/-/argparse-1.0.38.tgz#a81fd8606d481f873a3800c6ebae4f1d768a56a9"
@@ -2365,11 +2405,21 @@ acorn-jsx@^5.3.2:
   resolved "https://registry.yarnpkg.com/acorn-jsx/-/acorn-jsx-5.3.2.tgz#7ed5bb55908b3b2f1bc55c6af1653bada7f07937"
   integrity sha512-rq9s+JNhf0IChjtDXxllJ7g41oZk5SlXtp0LHwyA5cejwn7vKmKp4pPri6YEePv2PU65sAsegbXtIinmDFDXgQ==
 
+acorn-walk@^8.1.1:
+  version "8.3.2"
+  resolved "https://registry.yarnpkg.com/acorn-walk/-/acorn-walk-8.3.2.tgz#7703af9415f1b6db9315d6895503862e231d34aa"
+  integrity sha512-cjkyv4OtNCIeqhHrfS81QWXoCBPExR/J62oyEqepVw8WaQeSqpW2uhuLPh1m9eWhDuOo/jUXVTlifvesOWp/4A==
+
 acorn@^6.4.1:
   version "6.4.2"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-6.4.2.tgz#35866fd710528e92de10cf06016498e47e39e1e6"
   integrity sha512-XtGIhXwF8YM8bJhGxG5kXgjkEuNGLTkoYqVE+KMR+aspr4KGYmKYg7yUe3KghyQ9yheNwLnjmzh/7+gfDBmHCQ==
 
+acorn@^8.4.1:
+  version "8.11.3"
+  resolved "https://registry.yarnpkg.com/acorn/-/acorn-8.11.3.tgz#71e0b14e13a4ec160724b38fb7b0f233b1b81d7a"
+  integrity sha512-Y9rRfJG5jcKOE0CLisYbojUjIrIEE7AGMzA/Sm4BslANhbS+cDMpgBdcPT91oJ7OuJ9hYJBx59RjbhxVnrF8Xg==
+
 acorn@^8.9.0:
   version "8.10.0"
   resolved "https://registry.yarnpkg.com/acorn/-/acorn-8.10.0.tgz#8be5b3907a67221a81ab23c7889c4c5526b62ec5"
@@ -10984,6 +11034,25 @@ ts-jest@^29.0.5:
     semver "^7.5.3"
     yargs-parser "^21.0.1"
 
+ts-node@^10.0.0:
+  version "10.9.2"
+  resolved "https://registry.yarnpkg.com/ts-node/-/ts-node-10.9.2.tgz#70f021c9e185bccdca820e26dc413805c101c71f"
+  integrity sha512-f0FFpIdcHgn8zcPSbf1dRevwt047YMnaiJM3u2w2RewrB+fob/zePZcrOyQoLMMO7aBIddLcQIEK5dYjkLnGrQ==
+  dependencies:
+    "@cspotcode/source-map-support" "^0.8.0"
+    "@tsconfig/node10" "^1.0.7"
+    "@tsconfig/node12" "^1.0.7"
+    "@tsconfig/node14" "^1.0.0"
+    "@tsconfig/node16" "^1.0.2"
+    acorn "^8.4.1"
+    acorn-walk "^8.1.1"
+    arg "^4.1.0"
+    create-require "^1.1.0"
+    diff "^4.0.1"
+    make-error "^1.1.1"
+    v8-compile-cache-lib "^3.0.1"
+    yn "3.1.1"
+
 ts-node@^9.1.1:
   version "9.1.1"
   resolved "https://registry.yarnpkg.com/ts-node/-/ts-node-9.1.1.tgz#51a9a450a3e959401bda5f004a72d54b936d376d"
@@ -11410,6 +11479,11 @@ uuid@^9.0.0:
   resolved "https://registry.yarnpkg.com/uuid/-/uuid-9.0.0.tgz#592f550650024a38ceb0c562f2f6aa435761efb5"
   integrity sha512-MXcSTerfPa4uqyzStbRoTgt5XIe3x5+42+q1sDuy3R5MDk66URdLMOZe5aPX/SQd+kuYAh0FdP/pO28IkQyTeg==
 
+v8-compile-cache-lib@^3.0.1:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/v8-compile-cache-lib/-/v8-compile-cache-lib-3.0.1.tgz#6336e8d71965cb3d35a1bbb7868445a7c05264bf"
+  integrity sha512-wa7YjyUGfNZngI/vtK0UHAN+lgDCxBPCylVXGp0zu59Fz5aiGtNXaq3DhIov063MorB+VfufLh3JlF2KdTK3xg==
+
 v8-to-istanbul@^9.0.1:
   version "9.1.0"
   resolved "https://registry.yarnpkg.com/v8-to-istanbul/-/v8-to-istanbul-9.1.0.tgz#1b83ed4e397f58c85c266a570fc2558b5feb9265"

From 06ed223f03f2cb084791e224c871d7026c10ee40 Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 21:38:59 -0700
Subject: [PATCH 09/12] allow all extensions and detect tsx or ts-node

---
 ...-3e7ef03c-6140-4b48-b824-f7303ca53d62.json | 11 ++++++++++
 packages/just-task/src/config.ts              | 22 +++++++++++--------
 packages/just-task/src/enableTypeScript.ts    | 16 ++++++++++++++
 3 files changed, 40 insertions(+), 9 deletions(-)
 create mode 100644 change/change-3e7ef03c-6140-4b48-b824-f7303ca53d62.json

diff --git a/change/change-3e7ef03c-6140-4b48-b824-f7303ca53d62.json b/change/change-3e7ef03c-6140-4b48-b824-f7303ca53d62.json
new file mode 100644
index 00000000..18f56b40
--- /dev/null
+++ b/change/change-3e7ef03c-6140-4b48-b824-f7303ca53d62.json
@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "type": "patch",
+      "comment": "Detect if already running in ts-node or tsx and skip call to ts-node register",
+      "packageName": "just-task",
+      "email": "elcraig@microsoft.com",
+      "dependentChangeType": "patch"
+    }
+  ]
+}
\ No newline at end of file
diff --git a/packages/just-task/src/config.ts b/packages/just-task/src/config.ts
index be1c8c93..eedabcbe 100644
--- a/packages/just-task/src/config.ts
+++ b/packages/just-task/src/config.ts
@@ -42,15 +42,6 @@ export async function readConfig(): Promise<{ [key: string]: TaskFunction } | vo
 
   const ext = path.extname(configFile).toLowerCase();
 
-  if (ext === '.mts' || (packageIsESM && ext === '.ts')) {
-    // We can't support these with ts-node because we're calling register() rather than creating
-    // a child process with the custom --loader, and it appears that it's not possible to change
-    // the loader (needed for ESM) after the fact. The same limitation applies for tsx.
-    // https://typestrong.org/ts-node/docs/imports/#native-ecmascript-modules
-    logger.error('Just does not currently support ESM TypeScript configuration files. Please use a .cts file.');
-    process.exit(1);
-  }
-
   if (/^\.[cm]?ts$/.test(ext)) {
     const tsSuccess = enableTypeScript({ transpileOnly: true, configFile });
     if (!tsSuccess) {
@@ -68,6 +59,19 @@ export async function readConfig(): Promise<{ [key: string]: TaskFunction } | vo
   } catch (e) {
     logger.error(`Error loading configuration file: ${configFile}`);
     logger.error((e as Error).stack || (e as Error).message || e);
+
+    if (ext === '.mts' || (packageIsESM && ext === '.ts')) {
+      // We can't directly support these with ts-node because we're calling register() rather than
+      // creating a child process with the custom --loader.
+      // (Related: https://typestrong.org/ts-node/docs/imports/)
+      const binPath = path.relative(process.cwd(), process.argv[1]);
+      logger.error('');
+      logger.error(
+        'Just does not directly support ESM TypeScript configuration files. You must either ' +
+          `use a .cts file, or call the just binary (${binPath}) via ts-node or tsx.`,
+      );
+    }
+
     process.exit(1);
   }
 
diff --git a/packages/just-task/src/enableTypeScript.ts b/packages/just-task/src/enableTypeScript.ts
index d723b2f6..da3b9697 100644
--- a/packages/just-task/src/enableTypeScript.ts
+++ b/packages/just-task/src/enableTypeScript.ts
@@ -9,6 +9,22 @@ import { logger } from 'just-task-logger';
  */
 export function enableTypeScript(params: { transpileOnly?: boolean; configFile?: string }): boolean {
   const { transpileOnly = true, configFile = '' } = params;
+
+  // Try to determine if the user is already running with a known transpiler.
+  // ts-node makes this easy by setting process.env.TS_NODE.
+  // tsx doesn't set a variable, so check a few places it might show up.
+  const contextVals = [
+    ...process.argv,
+    ...process.execArgv,
+    process.env._,
+    process.env.npm_lifecycle_event,
+    process.env.npm_config_argv,
+  ];
+  if (process.env.TS_NODE || contextVals.some(val => /[^.]tsx\b/.test(val || ''))) {
+    // It appears the user ran the just CLI with tsx or ts-node, so allow this.
+    return true;
+  }
+
   const tsNodeModule = resolve('ts-node');
 
   if (!tsNodeModule) {

From c4763e24ed22cc3dcea7b8a7886a1ece4c745dbf Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 21:49:30 -0700
Subject: [PATCH 10/12] add ts-node-esm wrapped example lib

---
 packages/example-lib-esm-ts/just.config.cts       |  9 ++++++++-
 packages/example-lib-esm-tsnode/README.md         |  1 +
 packages/example-lib-esm-tsnode/just.config.ts    | 14 ++++++++++++++
 packages/example-lib-esm-tsnode/package.json      | 14 ++++++++++++++
 packages/example-lib-esm-tsnode/src/index.ts      |  1 +
 .../example-lib-esm-tsnode/tasks/customTask.ts    |  7 +++++++
 packages/example-lib-esm-tsnode/tsconfig.json     | 15 +++++++++++++++
 packages/example-lib/just.config.ts               |  9 ++++++++-
 .../just-scripts/src/typescript/getTsNodeEnv.ts   |  1 +
 9 files changed, 69 insertions(+), 2 deletions(-)
 create mode 100644 packages/example-lib-esm-tsnode/README.md
 create mode 100644 packages/example-lib-esm-tsnode/just.config.ts
 create mode 100644 packages/example-lib-esm-tsnode/package.json
 create mode 100644 packages/example-lib-esm-tsnode/src/index.ts
 create mode 100644 packages/example-lib-esm-tsnode/tasks/customTask.ts
 create mode 100644 packages/example-lib-esm-tsnode/tsconfig.json

diff --git a/packages/example-lib-esm-ts/just.config.cts b/packages/example-lib-esm-ts/just.config.cts
index c60b428a..10bbd7dc 100644
--- a/packages/example-lib-esm-ts/just.config.cts
+++ b/packages/example-lib-esm-ts/just.config.cts
@@ -2,6 +2,13 @@ import { nodeExecTask, tscTask, task, parallel } from 'just-scripts';
 
 task('typescript', tscTask({}));
 
-task('customNodeTask', nodeExecTask({ enableTypeScript: 'esm', args: ['./tasks/customTask.ts'] }));
+task(
+  'customNodeTask',
+  nodeExecTask({
+    enableTypeScript: 'esm',
+    transpileOnly: true,
+    args: ['./tasks/customTask.ts'],
+  }),
+);
 
 task('build', parallel('customNodeTask', 'typescript'));
diff --git a/packages/example-lib-esm-tsnode/README.md b/packages/example-lib-esm-tsnode/README.md
new file mode 100644
index 00000000..1c57c67b
--- /dev/null
+++ b/packages/example-lib-esm-tsnode/README.md
@@ -0,0 +1 @@
+This package has `"type": "module"` in its `package.json`. The config is a `.ts` which will be treated as ESM, and Just can't handle that directly (see [`example-lib-esm-ts` readme](../example-lib-esm-ts/README.md)). So the package's `"build"` script wraps the `just-scripts` binary with the transpiler: `ts-node-esm node_modules/.bin/just-scripts build`.
diff --git a/packages/example-lib-esm-tsnode/just.config.ts b/packages/example-lib-esm-tsnode/just.config.ts
new file mode 100644
index 00000000..10bbd7dc
--- /dev/null
+++ b/packages/example-lib-esm-tsnode/just.config.ts
@@ -0,0 +1,14 @@
+import { nodeExecTask, tscTask, task, parallel } from 'just-scripts';
+
+task('typescript', tscTask({}));
+
+task(
+  'customNodeTask',
+  nodeExecTask({
+    enableTypeScript: 'esm',
+    transpileOnly: true,
+    args: ['./tasks/customTask.ts'],
+  }),
+);
+
+task('build', parallel('customNodeTask', 'typescript'));
diff --git a/packages/example-lib-esm-tsnode/package.json b/packages/example-lib-esm-tsnode/package.json
new file mode 100644
index 00000000..3966ddd0
--- /dev/null
+++ b/packages/example-lib-esm-tsnode/package.json
@@ -0,0 +1,14 @@
+{
+  "name": "example-lib-esm-tsnode",
+  "private": true,
+  "version": "1.0.0",
+  "type": "module",
+  "scripts": {
+    "build": "ts-node-esm node_modules/.bin/just-scripts build"
+  },
+  "license": "MIT",
+  "devDependencies": {
+    "just-scripts": ">=2.2.3 <3.0.0",
+    "ts-node": "^10.0.0"
+  }
+}
diff --git a/packages/example-lib-esm-tsnode/src/index.ts b/packages/example-lib-esm-tsnode/src/index.ts
new file mode 100644
index 00000000..ef74d34b
--- /dev/null
+++ b/packages/example-lib-esm-tsnode/src/index.ts
@@ -0,0 +1 @@
+const a = 5;
diff --git a/packages/example-lib-esm-tsnode/tasks/customTask.ts b/packages/example-lib-esm-tsnode/tasks/customTask.ts
new file mode 100644
index 00000000..39731f3b
--- /dev/null
+++ b/packages/example-lib-esm-tsnode/tasks/customTask.ts
@@ -0,0 +1,7 @@
+import * as path from 'path';
+import * as fs from 'fs';
+import { fileURLToPath } from 'url';
+
+const dirname = path.dirname(fileURLToPath(import.meta.url));
+
+export const packageJson = fs.readFileSync(path.resolve(dirname, '../package.json'), 'utf-8');
diff --git a/packages/example-lib-esm-tsnode/tsconfig.json b/packages/example-lib-esm-tsnode/tsconfig.json
new file mode 100644
index 00000000..6ce85e60
--- /dev/null
+++ b/packages/example-lib-esm-tsnode/tsconfig.json
@@ -0,0 +1,15 @@
+{
+  "compilerOptions": {
+    "target": "ESNext",
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "declaration": true,
+    "declarationMap": true,
+    "outDir": "lib",
+    "strict": true,
+    "esModuleInterop": true,
+    "skipLibCheck": true,
+    "types": []
+  },
+  "include": ["src"]
+}
diff --git a/packages/example-lib/just.config.ts b/packages/example-lib/just.config.ts
index 02b8363f..54fda037 100644
--- a/packages/example-lib/just.config.ts
+++ b/packages/example-lib/just.config.ts
@@ -3,7 +3,14 @@ import { nodeExecTask, tscTask, task, parallel, watch } from 'just-scripts';
 task('typescript', tscTask({}));
 task('typescript:watch', tscTask({ watch: true }));
 
-task('customNodeTask', nodeExecTask({ enableTypeScript: true, args: ['./tasks/customTask.ts'] }));
+task(
+  'customNodeTask',
+  nodeExecTask({
+    enableTypeScript: true,
+    transpileOnly: true,
+    args: ['./tasks/customTask.ts'],
+  }),
+);
 
 task('build', parallel('customNodeTask', 'typescript'));
 task('watch', parallel('typescript:watch'));
diff --git a/packages/just-scripts/src/typescript/getTsNodeEnv.ts b/packages/just-scripts/src/typescript/getTsNodeEnv.ts
index daee4671..1e567300 100644
--- a/packages/just-scripts/src/typescript/getTsNodeEnv.ts
+++ b/packages/just-scripts/src/typescript/getTsNodeEnv.ts
@@ -15,6 +15,7 @@ export function getTsNodeEnv(
       target: 'es2017',
       moduleResolution: esm ? 'NodeNext' : 'node',
       module: esm ? 'NodeNext' : 'commonjs',
+      skipLibCheck: true,
     });
     logger.info(`[TS] Using these compilerOptions: ${compilerOptions}`);
     env.TS_NODE_COMPILER_OPTIONS = compilerOptions;

From 4f87ce1c685d4db9b394753637b4e624d5fa4ddc Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Thu, 14 Mar 2024 21:50:25 -0700
Subject: [PATCH 11/12] api

---
 packages/just-scripts/etc/just-scripts.api.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/just-scripts/etc/just-scripts.api.md b/packages/just-scripts/etc/just-scripts.api.md
index d2603b4a..5e228d9a 100644
--- a/packages/just-scripts/etc/just-scripts.api.md
+++ b/packages/just-scripts/etc/just-scripts.api.md
@@ -293,7 +293,7 @@ export function nodeExecTask(options: NodeExecTaskOptions): TaskFunction;
 // @public (undocumented)
 export interface NodeExecTaskOptions {
     args?: string[];
-    enableTypeScript?: boolean;
+    enableTypeScript?: boolean | 'esm';
     env?: NodeJS.ProcessEnv;
     spawnOptions?: SpawnOptions;
     transpileOnly?: boolean;

From 9d38a18f5872399a928348c261bb52d4fb6af9a7 Mon Sep 17 00:00:00 2001
From: Elizabeth Craig <elcraig@microsoft.com>
Date: Fri, 15 Mar 2024 10:41:19 -0700
Subject: [PATCH 12/12] syncpack

---
 package.json | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/package.json b/package.json
index fcc25db8..87a3a9c8 100644
--- a/package.json
+++ b/package.json
@@ -74,6 +74,18 @@
     "dependencyTypes": [
       "dev",
       "prod"
+    ],
+    "versionGroups": [
+      {
+        "label": "ts-node (testing with multiple versions)",
+        "dependencies": [
+          "ts-node"
+        ],
+        "packages": [
+          "**"
+        ],
+        "isIgnored": true
+      }
     ]
   },
   "workspaces": {