docs: unify __dirname usage (#19176)

docs/guide/api-environment-frameworks.md

@@ -46,8 +46,13 @@ The `runner` is evaluated eagerly when it's accessed for the first time. Beware
 Given a Vite server configured in middleware mode as described by the [SSR setup guide](/guide/ssr#setting-up-the-dev-server), let's implement the SSR middleware using the environment API. Error handling is omitted.
 
 ```js
+import fs from 'node:fs'
+import path from 'node:path'
+import { fileURLToPath } from 'node:url'
 import { createServer } from 'vite'
 
+const __dirname = path.dirname(fileURLToPath(import.meta.url))
+
 const server = await createServer({
   server: { middlewareMode: true },
   appType: 'custom',

docs/guide/build.md

@@ -106,9 +106,12 @@ During dev, simply navigate or link to `/nested/` - it works as expected, just l
 During build, all you need to do is to specify multiple `.html` files as entry points:
 
 ```js twoslash [vite.config.js]
-import { resolve } from 'path'
+import { dirname, resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
 import { defineConfig } from 'vite'
 
+const __dirname = dirname(fileURLToPath(import.meta.url))
+
 export default defineConfig({
   build: {
     rollupOptions: {
@@ -134,9 +137,12 @@ When it is time to bundle your library for distribution, use the [`build.lib` co
 ::: code-group
 
 ```js twoslash [vite.config.js (single entry)]
-import { resolve } from 'path'
+import { dirname, resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
 import { defineConfig } from 'vite'
 
+const __dirname = dirname(fileURLToPath(import.meta.url))
+
 export default defineConfig({
   build: {
     lib: {
@@ -162,9 +168,12 @@ export default defineConfig({
 ```
 
 ```js twoslash [vite.config.js (multiple entries)]
-import { resolve } from 'path'
+import { dirname, resolve } from 'node:path'
+import { fileURLToPath } from 'node:url'
 import { defineConfig } from 'vite'
 
+const __dirname = dirname(fileURLToPath(import.meta.url))
+
 export default defineConfig({
   build: {
     lib: {