[ESM] Support wrapping a custom loader

.eslintrc

@@ -18,6 +18,7 @@
     {
       "files": ["./**/*.mjs"],
       "parserOptions": {
+        "ecmaVersion": 2022,
         "sourceType": "module"
       }
     }

lib/cli.js

@@ -16,7 +16,7 @@ const nodeString = ['require'];
 
 const nodeDevBoolean = ['clear', 'dedupe', 'fork', 'notify', 'poll', 'respawn', 'vm'];
 const nodeDevNumber = ['debounce', 'deps', 'interval'];
-const nodeDevString = ['graceful_ipc', 'ignore', 'timestamp'];
+const nodeDevString = ['graceful_ipc', 'ignore', 'timestamp', 'experimental-loader'];
 
 const alias = Object.assign({}, nodeAlias);
 const boolean = [...nodeBoolean, ...nodeDevBoolean];

lib/index.js

@@ -21,6 +21,7 @@ module.exports = function (
     debounce,
     dedupe,
     deps,
+    'experimental-loader': customLoader,
     graceful_ipc: gracefulIPC,
     ignore,
     interval,
@@ -97,18 +98,19 @@ module.exports = function (
     const args = nodeArgs.slice();
 
     if (extname(script) === '.mjs' || getPackageType.sync(script) === 'module') {
+      const customLoaderQs = customLoader ? `?${new URLSearchParams({ customLoader: resolveMain(customLoader) }).toString()}` : '';
       if (semver.satisfies(process.version, '>=10 <12.11.1')) {
         const resolveLoader = resolveMain(localPath('resolve-loader.mjs'));
-        args.push('--experimental-modules', `--loader=${resolveLoader}`);
+        args.push('--experimental-modules', `--loader=${resolveLoader + customLoaderQs}`);
       } else if (semver.satisfies(process.version, '>=12.11.1')) {
         if (semver.satisfies(process.version, '<12.17.0')) {
           args.push('--experimental-modules');
         }
-        const loaderPath = semver.satisfies(process.version, '>=16.12.0')
+        let loaderPath = semver.satisfies(process.version, '>=16.12.0')
           ? 'load-loader.mjs'
           : 'get-source-loader.mjs';
         const experimentalLoader = resolveMain(localPath(loaderPath));
-        args.push(`--experimental-loader=${experimentalLoader}`);
+        args.push(`--experimental-loader=${experimentalLoader + customLoaderQs}`);
       }
     }
 

lib/load-loader.mjs

@@ -1,6 +1,10 @@
 import { send } from './ipc.js';
 
+const customLoaderUrl = new URL(import.meta.url).searchParams.get('customLoader');
+const customLoader = customLoaderUrl ? await import(customLoaderUrl) : {};
+
 export async function load(url, context, defaultLoad) {
   send({ required: new URL(url).pathname });
-  return defaultLoad(url, context, defaultLoad);
+  const customLoad = customLoader.load || defaultLoad;
+  return customLoad(url, context, defaultLoad);
 }