feat(esm/api): tsImport() to support loading CommonJS files

Author: privatenumber

docs/node/ts-import.md

@@ -8,10 +8,6 @@ The current file path must be passed in as the second argument to resolve the im
 
 Since this is designed for one-time use, it does not cache loaded modules.
 
-::: warning Caveat
-CommonJS files are currently not enhanced due to this [Node.js bug](https://github.com/nodejs/node/issues/51327).
-:::
-
 ## ESM usage
 
 ```js

src/cjs/api/module-resolve-filename.ts

@@ -26,8 +26,13 @@ export const interopCjsExports = (
 	}
 
 	const searchParams = new URLSearchParams(request.slice(queryIndex + 1));
-	const realPath = searchParams.get('filePath');
+	let realPath = searchParams.get('filePath');
 	if (realPath) {
+		const namespace = searchParams.get('namespace');
+		if (namespace) {
+			realPath += `?namespace=${encodeURIComponent(namespace)}`;
+		}
+
 		// The CJS module cache needs to be updated with the actual path for export parsing to work
 		// https://github.com/nodejs/node/blob/v22.2.0/lib/internal/modules/esm/translators.js#L338
 		Module._cache[realPath] = Module._cache[request];

src/esm/api/ts-import.ts

@@ -1,3 +1,4 @@
+import { register as cjsRegister } from '../../cjs/api/index.js';
 import { register, type TsconfigOptions } from './register.js';
 
 type Options = {
@@ -20,6 +21,11 @@ const tsImport = (
 	const parentURL = isOptionsString ? options : options.parentURL;
 	const namespace = Date.now().toString();
 
+	// Keep registered for hanging require() calls
+	cjsRegister({
+		namespace,
+	});
+
 	/**
 	 * We don't want to unregister this after load since there can be child import() calls
 	 * that need TS support

src/esm/hook/load.ts

@@ -29,7 +29,8 @@ export const load: LoadHook = async (
 		return nextLoad(url, context);
 	}
 
-	if (data.namespace && data.namespace !== getNamespace(url)) {
+	const urlNamespace = getNamespace(url);
+	if (data.namespace && data.namespace !== urlNamespace) {
 		return nextLoad(url, context);
 	}
 
@@ -76,6 +77,9 @@ export const load: LoadHook = async (
 				exports.map(exported => exported.n).filter(name => name !== 'default').join(',')
 			}}`;
 			const parameters = new URLSearchParams({ filePath });
+			if (urlNamespace) {
+				parameters.set('namespace', urlNamespace);
+			}
 			loaded.responseURL = `data:text/javascript,${encodeURIComponent(cjsExports)}?${parameters.toString()}`;
 		}
 

tests/specs/api.ts

@@ -23,6 +23,7 @@ const tsFiles = {
 	export const foo = \`foo \${bar}\` as string
 	export const async = setTimeout(10).then(() => require('./async')).catch((error) => error);
 	`,
+	'cts.cts': 'export const cts = \'cts\' as string',
 	'bar.ts': 'export type A = 1; export { bar } from "pkg"',
 	'async.ts': 'export default "async"',
 	'node_modules/pkg': {
@@ -507,6 +508,9 @@ export default testSuite(({ describe }, node: NodeApis) => {
 							const { message } = await tsImport('./file.ts', import.meta.url);
 							console.log(message);
 
+							const cts = await tsImport('./cts.cts', import.meta.url).then(m => m.cts, err => err.constructor.name);
+							console.log(cts);
+
 							const { message: message2 } = await tsImport('./file.ts?with-query', import.meta.url);
 							console.log(message2);
 
@@ -522,7 +526,12 @@ export default testSuite(({ describe }, node: NodeApis) => {
 							nodePath: node.path,
 							nodeOptions: [],
 						});
-						expect(stdout).toMatch(/Fails as expected 1\nfoo bar file\.ts\?tsx-namespace=\d+\nfoo bar file\.ts\?with-query=&tsx-namespace=\d+\nFails as expected 2/);
+
+						if (node.supports.cjsInterop) {
+							expect(stdout).toMatch(/Fails as expected 1\nfoo bar file\.ts\?tsx-namespace=\d+\ncts\nfoo bar file\.ts\?with-query=&tsx-namespace=\d+\nFails as expected 2/);
+						} else {
+							expect(stdout).toMatch(/Fails as expected 1\nfoo bar file\.ts\?tsx-namespace=\d+\nSyntaxError\nfoo bar file\.ts\?with-query=&tsx-namespace=\d+\nFails as expected 2/);
+						}
 					});
 
 					test('commonjs', async () => {