feat: format default to 'esm'

packages/core/src/config.ts

@@ -841,6 +841,7 @@ const composeExternalsConfig = (
 
 const composeAutoExtensionConfig = (
   config: LibConfig,
+  format: Format,
   autoExtension: boolean,
   pkgJson?: PkgJson,
 ): {
@@ -849,7 +850,7 @@ const composeAutoExtensionConfig = (
   dtsExtension: string;
 } => {
   const { jsExtension, dtsExtension } = getDefaultExtension({
-    format: config.format!,
+    format,
     pkgJson,
     autoExtension,
   });
@@ -1307,9 +1308,10 @@ const composeBundlelessExternalConfig = (
 
 const composeDtsConfig = async (
   libConfig: LibConfig,
+  format: Format,
   dtsExtension: string,
 ): Promise<EnvironmentConfig> => {
-  const { format, autoExternal, banner, footer, redirect } = libConfig;
+  const { autoExternal, banner, footer, redirect } = libConfig;
 
   let { dts } = libConfig;
 
@@ -1332,7 +1334,7 @@ const composeDtsConfig = async (
         build: dts?.build,
         abortOnError: dts?.abortOnError,
         dtsExtension: dts?.autoExtension ? dtsExtension : '.d.ts',
-        autoExternal: getAutoExternalDefaultValue(format!, autoExternal),
+        autoExternal: getAutoExternalDefaultValue(format, autoExternal),
         banner: banner?.dts,
         footer: footer?.dts,
         redirect: redirect?.dts,
@@ -1454,7 +1456,7 @@ async function composeLibRsbuildConfig(
   const cssModulesAuto = config.output?.cssModules?.auto ?? true;
 
   const {
-    format,
+    format = 'esm',
     shims,
     bundle = true,
     banner = {},
@@ -1466,11 +1468,11 @@ async function composeLibRsbuildConfig(
     umdName,
   } = config;
   const { rsbuildConfig: shimsConfig, enabledShims } = composeShimsConfig(
-    format!,
+    format,
     shims,
   );
   const formatConfig = composeFormatConfig({
-    format: format!,
+    format,
     pkgJson: pkgJson!,
     bundle,
     umdName,
@@ -1480,14 +1482,14 @@ async function composeLibRsbuildConfig(
     pkgJson,
   );
   const userExternalsConfig = composeExternalsConfig(
-    format!,
+    format,
     config.output?.externals,
   );
   const {
     config: autoExtensionConfig,
     jsExtension,
     dtsExtension,
-  } = composeAutoExtensionConfig(config, autoExtension, pkgJson);
+  } = composeAutoExtensionConfig(config, format, autoExtension, pkgJson);
   const { entryConfig, outBase } = await composeEntryConfig(
     config.source?.entry!,
     config.bundle,
@@ -1506,11 +1508,11 @@ async function composeLibRsbuildConfig(
     config: targetConfig,
     externalsConfig: targetExternalsConfig,
     target,
-  } = composeTargetConfig(config.output?.target, format!);
+  } = composeTargetConfig(config.output?.target, format);
   const syntaxConfig = composeSyntaxConfig(target, config?.syntax);
   const autoExternalConfig = composeAutoExternalConfig({
     bundle,
-    format: format!,
+    format,
     autoExternal,
     pkgJson,
     userExternals: config.output?.externals,
@@ -1522,15 +1524,15 @@ async function composeLibRsbuildConfig(
     banner?.css,
     footer?.css,
   );
-  const assetConfig = composeAssetConfig(bundle, format!);
+  const assetConfig = composeAssetConfig(bundle, format);
 
   const entryChunkConfig = composeEntryChunkConfig({
     enabledImportMetaUrlShim: enabledShims.cjs['import.meta.url'],
     contextToWatch: outBase,
   });
-  const dtsConfig = await composeDtsConfig(config, dtsExtension);
+  const dtsConfig = await composeDtsConfig(config, format, dtsExtension);
   const externalsWarnConfig = composeExternalsWarnConfig(
-    format!,
+    format,
     userExternalsConfig?.output?.externals,
     autoExternalConfig?.output?.externals,
   );
@@ -1619,7 +1621,7 @@ export async function composeCreateRsbuildConfig(
     delete userConfig.output.externals;
 
     const config: RsbuildConfigWithLibInfo = {
-      format: libConfig.format!,
+      format: libConfig.format ?? 'esm',
       // The merge order represents the priority of the configuration
       // The priorities from high to low are as follows:
       // 1 - userConfig: users can configure any Rsbuild and Rspack config

packages/core/src/types/config.ts

@@ -215,7 +215,7 @@ export interface LibConfig extends EnvironmentConfig {
   id?: string;
   /**
    * Output format for the generated JavaScript files.
-   * @defaultValue `undefined`
+   * @defaultValue `'esm'`
    * @see {@link https://lib.rsbuild.dev/config/lib/format}
    */
   format?: Format;

tests/integration/format/cjs-static-export/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "format-cjs-static-export-test",
+  "version": "1.0.0",
+  "private": true,
+  "type": "module"
+}

tests/integration/format/package.json → tests/integration/format/default/package.json

@@ -1,5 +1,5 @@
 {
-  "name": "format-test",
+  "name": "format-default-test",
   "version": "1.0.0",
   "private": true,
   "type": "module"

tests/integration/format/default/rslib.config.ts

@@ -0,0 +1,37 @@
+import { defineConfig } from '@rslib/core';
+import { generateBundleCjsConfig, generateBundleEsmConfig } from 'test-helper';
+
+export default defineConfig({
+  lib: [
+    generateBundleEsmConfig({
+      output: {
+        distPath: {
+          root: './dist/bundle-esm',
+        },
+      },
+    }),
+    generateBundleCjsConfig({
+      output: {
+        distPath: {
+          root: './dist/bundle-cjs',
+        },
+      },
+    }),
+    generateBundleEsmConfig({
+      bundle: false,
+      output: {
+        distPath: {
+          root: './dist/bundleless-esm',
+        },
+      },
+    }),
+    generateBundleCjsConfig({
+      bundle: false,
+      output: {
+        distPath: {
+          root: './dist/bundleless-cjs',
+        },
+      },
+    }),
+  ],
+});

tests/integration/format/default/src/foo.js

@@ -0,0 +1 @@
+export const foo = 'foo';

tests/integration/format/default/src/index.js

@@ -0,0 +1,3 @@
+import { foo } from './foo';
+
+export const str = 'hello' + foo + ' world';

tests/integration/format/import-meta-url/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "format-import-meta-url-test",
+  "version": "1.0.0",
+  "private": true,
+  "type": "module"
+}

tests/integration/format/index.test.ts

@@ -2,6 +2,53 @@ import path from 'node:path';
 import { buildAndGetResults } from 'test-helper';
 import { expect, test } from 'vitest';
 
+test('format default to esm', async () => {
+  const fixturePath = path.resolve(__dirname, 'default');
+  const { files, contents } = await buildAndGetResults({
+    fixturePath,
+  });
+
+  expect(files).toMatchInlineSnapshot(`
+    {
+      "cjs0": [
+        "<ROOT>/tests/integration/format/default/dist/bundle-cjs/index.cjs",
+      ],
+      "cjs1": [
+        "<ROOT>/tests/integration/format/default/dist/bundleless-cjs/foo.cjs",
+        "<ROOT>/tests/integration/format/default/dist/bundleless-cjs/index.cjs",
+      ],
+      "esm0": [
+        "<ROOT>/tests/integration/format/default/dist/bundle-esm/index.js",
+      ],
+      "esm1": [
+        "<ROOT>/tests/integration/format/default/dist/bundleless-esm/foo.js",
+        "<ROOT>/tests/integration/format/default/dist/bundleless-esm/index.js",
+      ],
+    }
+  `);
+
+  expect(contents.esm0).toMatchInlineSnapshot(`
+    {
+      "<ROOT>/tests/integration/format/default/dist/bundle-esm/index.js": "const foo = 'foo';
+    const str = 'hello' + foo + ' world';
+    export { str };
+    ",
+    }
+  `);
+
+  expect(contents.esm1).toMatchInlineSnapshot(`
+    {
+      "<ROOT>/tests/integration/format/default/dist/bundleless-esm/foo.js": "const foo = 'foo';
+    export { foo };
+    ",
+      "<ROOT>/tests/integration/format/default/dist/bundleless-esm/index.js": "import * as __WEBPACK_EXTERNAL_MODULE__foo_js_fdf5aa2d__ from "./foo.js";
+    const str = 'hello' + __WEBPACK_EXTERNAL_MODULE__foo_js_fdf5aa2d__.foo + ' world';
+    export { str };
+    ",
+    }
+  `);
+});
+
 test('import.meta.url should be preserved', async () => {
   const fixturePath = path.resolve(__dirname, 'import-meta-url');
   const { files, entries, entryFiles } = await buildAndGetResults({

tests/scripts/shared.ts

@@ -20,7 +20,6 @@ export function getCwdByExample(exampleName: string) {
 
 export function generateBundleEsmConfig(config: LibConfig = {}): LibConfig {
   const esmBasicConfig: LibConfig = {
-    format: 'esm',
     output: {
       distPath: {
         root: './dist/esm',
@@ -107,19 +106,19 @@ export async function getResults(
   let key = '';
 
   const formatCount: Record<Format, number> = rslibConfig.lib.reduce(
-    (acc, { format }) => {
-      acc[format!] = (acc[format!] ?? 0) + 1;
+    (acc, { format = 'esm' }) => {
+      acc[format] = (acc[format] ?? 0) + 1;
       return acc;
     },
     {} as Record<Format, number>,
   );
 
   for (const libConfig of rslibConfig.lib) {
-    const { format } = libConfig;
-    const currentFormatCount = formatCount[format!];
-    const currentFormatIndex = formatIndex[format!]++;
+    const { format = 'esm' } = libConfig;
+    const currentFormatCount = formatCount[format];
+    const currentFormatIndex = formatIndex[format]++;
 
-    key = currentFormatCount === 1 ? format! : `${format}${currentFormatIndex}`;
+    key = currentFormatCount === 1 ? format : `${format}${currentFormatIndex}`;
 
     let globFolder = '';
     if (type === 'js' || type === 'css') {

website/docs/en/config/lib/format.mdx

@@ -1,8 +1,7 @@
 # lib.format
 
 - **Type:** `'esm' | 'cjs' | 'umd' | 'mf'`
-- **Default:** `undefined`
-- **Required**: true
+- **Default:** `'esm'`
 
 Specify the output format for the generated JavaScript output files.
 

website/docs/zh/config/lib/format.mdx

@@ -1,8 +1,7 @@
 # lib.format
 
 - **类型：** `'esm' | 'cjs' | 'umd' | 'mf'`
-- **默认值：** `undefined`
-- **必填：** 是
+- **默认值：** `'esm'`
 
 指定生成的 JavaScript 产物的输出格式。