fix(cli): load default exports from JavaScript config

cli/src/config.ts

@@ -137,11 +137,14 @@ async function loadExtConfigJS(
   extConfigFilePath: string,
 ): Promise<ExtConfigPairs> {
   try {
+    const extConfigObject = await require(extConfigFilePath);
+    const extConfig = extConfigObject.default ? await extConfigObject.default : extConfigObject;
+
     return {
       extConfigType: 'js',
       extConfigName,
       extConfigFilePath: extConfigFilePath,
-      extConfig: await require(extConfigFilePath),
+      extConfig,
     };
   } catch (e: any) {
     fatal(`Parsing ${c.strong(extConfigName)} failed.\n\n${e.stack ?? e}`);

cli/test/config.spec.ts

@@ -0,0 +1,50 @@
+import { execFileSync } from 'child_process';
+import { mkdtemp, remove, writeFile, writeJSON } from 'fs-extra';
+import { tmpdir } from 'os';
+import { join, resolve } from 'path';
+
+describe('JavaScript configuration', () => {
+  let appDir: string;
+
+  beforeEach(async () => {
+    appDir = await mkdtemp(join(tmpdir(), 'capacitor-config-'));
+  });
+
+  afterEach(async () => {
+    await remove(appDir);
+  });
+
+  it.each([
+    ['CommonJS', 'commonjs', 'module.exports ='],
+    ['ES module', 'module', 'export default'],
+  ])('loads a %s configuration', async (_name, type, exportStatement) => {
+    await writeJSON(join(appDir, 'package.json'), { name: 'config-test', type });
+    const expected = {
+      appId: 'com.example.config',
+      appName: 'Config Test',
+      webDir: 'build/frontend',
+      server: { url: 'http://localhost:5173', cleartext: true },
+    };
+    await writeFile(join(appDir, 'capacitor.config.js'), `${exportStatement} ${JSON.stringify(expected)};`);
+
+    // Use Node's module loader, as Jest transforms ES modules into CommonJS.
+    const configPath = resolve(__dirname, '../dist/config.js');
+    const output = execFileSync(
+      process.execPath,
+      [
+        '-e',
+        `require(${JSON.stringify(configPath)}).loadConfig().then(({ app }) => {
+          console.log(JSON.stringify({ appId: app.appId, appName: app.appName, webDir: app.webDir, extConfig: app.extConfig }));
+        }).catch(error => { console.error(error); process.exitCode = 1; });`,
+      ],
+      { cwd: appDir, encoding: 'utf8', timeout: 10000 },
+    );
+
+    expect(JSON.parse(output)).toEqual({
+      appId: expected.appId,
+      appName: expected.appName,
+      webDir: expected.webDir,
+      extConfig: expected,
+    });
+  });
+});