From 040ca9f2fdfb88c50107186bd93d4deb32f251c7 Mon Sep 17 00:00:00 2001
From: Anthony Fu <anthonyfu117@hotmail.com>
Date: Fri, 3 Jun 2022 21:39:58 +0800
Subject: [PATCH] feat: new `ssr.fileExtension` option

---
 packages/vite/src/node/build.ts  | 8 ++++----
 packages/vite/src/node/config.ts | 9 ++++++++-
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/packages/vite/src/node/build.ts b/packages/vite/src/node/build.ts
index 705465400ca5ca..9f22e54d9d5b61 100644
--- a/packages/vite/src/node/build.ts
+++ b/packages/vite/src/node/build.ts
@@ -21,7 +21,7 @@ import commonjsPlugin from '@rollup/plugin-commonjs'
 import type { RollupCommonJSOptions } from 'types/commonjs'
 import type { RollupDynamicImportVarsOptions } from 'types/dynamicImportVars'
 import type { TransformOptions } from 'esbuild'
-import type { InlineConfig, ResolvedConfig } from './config'
+import type { InlineConfig, JsExt, ResolvedConfig } from './config'
 import { isDepsOptimizerEnabled, resolveConfig } from './config'
 import { buildReporterPlugin } from './plugins/reporter'
 import { buildEsbuildPlugin } from './plugins/esbuild'
@@ -451,8 +451,10 @@ async function doBuild(
       const format = output.format || (cjsSsrBuild ? 'cjs' : 'es')
       const jsExt =
         (ssr && config.ssr?.target !== 'webworker') || libOptions
-          ? resolveOutputJsExtension(format, getPkgJson(config.root)?.type)
+          ? config.ssr?.fileExtension ||
+            resolveOutputJsExtension(format, getPkgJson(config.root)?.type)
           : 'js'
+
       return {
         dir: outDir,
         // Default format is 'es' for regular and for SSR builds
@@ -606,8 +608,6 @@ function getPkgName(name: string) {
   return name?.startsWith('@') ? name.split('/')[1] : name
 }
 
-type JsExt = 'js' | 'cjs' | 'mjs'
-
 function resolveOutputJsExtension(
   format: ModuleFormat,
   type: string = 'commonjs'
diff --git a/packages/vite/src/node/config.ts b/packages/vite/src/node/config.ts
index d80f5a60583abc..67875e068f44e7 100644
--- a/packages/vite/src/node/config.ts
+++ b/packages/vite/src/node/config.ts
@@ -228,6 +228,8 @@ export interface ExperimentalOptions {
   importGlobRestoreExtension?: boolean
 }
 
+export type JsExt = 'js' | 'cjs' | 'mjs'
+
 export type SSRTarget = 'node' | 'webworker'
 
 export type SSRFormat = 'esm' | 'cjs'
@@ -238,7 +240,7 @@ export interface SSROptions {
   /**
    * Define the target for the ssr build. The browser field in package.json
    * is ignored for node but used if webworker is the target
-   * Default: 'node'
+   * @default 'node'
    */
   target?: SSRTarget
   /**
@@ -249,6 +251,11 @@ export interface SSROptions {
    * @experimental
    */
   format?: SSRFormat
+  /**
+   * File extension of generated bundles
+   * Will infer from root package.json's "type" field if not specified
+   */
+  fileExtension?: JsExt
 }
 
 export interface ResolveWorkerOptions {