fix: only downgrade target to es2019 when actually using terser

Author: yyx990803

docs/config/index.md

@@ -437,7 +437,6 @@ export default async ({ command, mode }) => {
 
   When using `server.middlewareMode` and `server.https`, setting `server.hmr.server` to your HTTPS server will process HMR secure connection requests through your server. This can be helpful when using self-signed certificates.
 
-
 ### server.watch
 
 - **Type:** `object`
@@ -456,6 +455,7 @@ export default async ({ command, mode }) => {
 - **Related:** [SSR - Setting Up the Dev Server](/guide/ssr#setting-up-the-dev-server)
 
 - **Example:**
+
 ```js
 const express = require('express')
 const { createServer: createViteServer } = require('vite')
@@ -524,7 +524,10 @@ createServer()
 
   Browser compatibility target for the final bundle. The default value is a Vite special value, `'modules'`, which targets [browsers with native ES module support](https://caniuse.com/es6-module).
 
-  Another special value is 'esnext' - which only performs minimal transpiling (for minification compat) and assumes native dynamic imports support.
+  Another special value is `'esnext'` - which assumes native dynamic imports support and will transpile as little as possible:
+
+  - If the [`build.minify`](#build-minify) option is `'terser'` (the default), `'esnext'` will be forced down to `'es2019'`.
+  - In other cases, it will perform no transpilation at all.
 
   The transform is performed with esbuild and the value should be a valid [esbuild target option](https://esbuild.github.io/api/#target). Custom targets can either be a ES version (e.g. `es2015`), a browser with version (e.g. `chrome58`), or an array of multiple target strings.
 

packages/vite/src/node/build.ts

@@ -241,7 +241,7 @@ export function resolveBuildOptions(raw?: BuildOptions): ResolvedBuildOptions {
       'chrome87',
       'safari13.1'
     ]
-  } else if (resolved.target === 'esnext' && resolved.minify !== 'esbuild') {
+  } else if (resolved.target === 'esnext' && resolved.minify === 'terser') {
     // esnext + terser: limit to es2019 so it can be minified by terser
     resolved.target = 'es2019'
   }

packages/vite/src/node/plugins/esbuild.ts

@@ -127,7 +127,7 @@ export const buildEsbuildPlugin = (config: ResolvedConfig): Plugin => {
 
       const target = config.build.target
       const minify = config.build.minify === 'esbuild'
-      if (!target && !minify) {
+      if ((!target || target === 'esnext') && !minify) {
         return null
       }
       return transformWithEsbuild(code, chunk.fileName, {