feat: expose default mainFields/conditions (vitejs#18648)

docs/config/shared-options.md

@@ -117,7 +117,7 @@ For SSR builds, deduplication does not work for ESM build outputs configured fro
 ## resolve.conditions
 
 - **Type:** `string[]`
-- **Default:** `['module', 'browser', 'development|production']`
+- **Default:** `['module', 'browser', 'development|production']` (`defaultClientConditions`)
 
 Additional allowed conditions when resolving [Conditional Exports](https://nodejs.org/api/packages.html#packages_conditional_exports) from a package.
 
@@ -147,7 +147,7 @@ Export keys ending with "/" is deprecated by Node and may not work well. Please
 ## resolve.mainFields
 
 - **Type:** `string[]`
-- **Default:** `['browser', 'module', 'jsnext:main', 'jsnext']`
+- **Default:** `['browser', 'module', 'jsnext:main', 'jsnext']` (`defaultClientMainFields`)
 
 List of fields in `package.json` to try when resolving a package's entry point. Note this takes lower precedence than conditional exports resolved from the `exports` field: if an entry point is successfully resolved from `exports`, the main field will be ignored.
 

docs/config/ssr-options.md

@@ -34,7 +34,7 @@ Build target for the SSR server.
 ## ssr.resolve.conditions
 
 - **Type:** `string[]`
-- **Default:** `['module', 'node', 'development|production']` (`['module', 'browser', 'development|production']` for `ssr.target === 'webworker'`)
+- **Default:** `['module', 'node', 'development|production']` (`defaultServerConditions`) (`['module', 'browser', 'development|production']` (`defaultClientConditions`) for `ssr.target === 'webworker'`)
 - **Related:** [Resolve Conditions](./shared-options.md#resolve-conditions)
 
 These conditions are used in the plugin pipeline, and only affect non-externalized dependencies during the SSR build. Use `ssr.resolve.externalConditions` to affect externalized imports.

docs/guide/migration.md

@@ -24,10 +24,10 @@ The conditions that are no longer added internally for
 - `resolve.conditions` are `['module', 'browser', 'development|production']`
 - `ssr.resolve.conditions` are `['module', 'node', 'development|production']`
 
-The default values for those options are updated to the corresponding values and `ssr.resolve.conditions` no longer uses `resolve.conditions` as the default value. Note that `development|production` is a special variable that is replaced with `production` or `development` depending on the value of `process.env.NODE_ENV`.
+The default values for those options are updated to the corresponding values and `ssr.resolve.conditions` no longer uses `resolve.conditions` as the default value. Note that `development|production` is a special variable that is replaced with `production` or `development` depending on the value of `process.env.NODE_ENV`. These default values are exported from `vite` as `defaultClientConditions` and `defaultServerConditions`.
 
 If you specified a custom value for `resolve.conditions` or `ssr.resolve.conditions`, you need to update it to include the new conditions.
-For example, if you previously specified `['custom']` for `resolve.conditions`, you need to specify `['custom', 'module', 'browser', 'development|production']` instead.
+For example, if you previously specified `['custom']` for `resolve.conditions`, you need to specify `['custom', ...defaultClientConditions]` instead.
 
 ### JSON stringify
 

packages/vite/src/node/constants.ts

@@ -45,9 +45,9 @@ const DEFAULT_MAIN_FIELDS = [
   'jsnext:main', // moment still uses this...
   'jsnext',
 ]
-export const DEFAULT_CLIENT_MAIN_FIELDS = DEFAULT_MAIN_FIELDS
-export const DEFAULT_SERVER_MAIN_FIELDS = DEFAULT_MAIN_FIELDS.filter(
-  (f) => f !== 'browser',
+export const DEFAULT_CLIENT_MAIN_FIELDS = Object.freeze(DEFAULT_MAIN_FIELDS)
+export const DEFAULT_SERVER_MAIN_FIELDS = Object.freeze(
+  DEFAULT_MAIN_FIELDS.filter((f) => f !== 'browser'),
 )
 
 /**
@@ -57,11 +57,11 @@ export const DEFAULT_SERVER_MAIN_FIELDS = DEFAULT_MAIN_FIELDS.filter(
 export const DEV_PROD_CONDITION = `development|production` as const
 
 const DEFAULT_CONDITIONS = ['module', 'browser', 'node', DEV_PROD_CONDITION]
-export const DEFAULT_CLIENT_CONDITIONS = DEFAULT_CONDITIONS.filter(
-  (c) => c !== 'node',
+export const DEFAULT_CLIENT_CONDITIONS = Object.freeze(
+  DEFAULT_CONDITIONS.filter((c) => c !== 'node'),
 )
-export const DEFAULT_SERVER_CONDITIONS = DEFAULT_CONDITIONS.filter(
-  (c) => c !== 'browser',
+export const DEFAULT_SERVER_CONDITIONS = Object.freeze(
+  DEFAULT_CONDITIONS.filter((c) => c !== 'browser'),
 )
 
 // Baseline support browserslist

packages/vite/src/node/publicUtils.ts

@@ -3,7 +3,13 @@
  * This file will be bundled to ESM and CJS and redirected by ../index.cjs
  * Please control the side-effects by checking the ./dist/node-cjs/publicUtils.cjs bundle
  */
-export { VERSION as version } from './constants'
+export {
+  VERSION as version,
+  DEFAULT_CLIENT_CONDITIONS as defaultClientConditions,
+  DEFAULT_CLIENT_MAIN_FIELDS as defaultClientMainFields,
+  DEFAULT_SERVER_CONDITIONS as defaultServerConditions,
+  DEFAULT_SERVER_MAIN_FIELDS as defaultServerMainFields,
+} from './constants'
 export { version as esbuildVersion } from 'esbuild'
 export {
   splitVendorChunkPlugin,

packages/vite/src/node/utils.ts

@@ -1070,27 +1070,36 @@ function backwardCompatibleWorkerPlugins(plugins: any) {
   return []
 }
 
-function deepClone<T>(value: T): T {
+type DeepWritable<T> =
+  T extends ReadonlyArray<unknown>
+    ? { -readonly [P in keyof T]: DeepWritable<T[P]> }
+    : T extends RegExp
+      ? RegExp
+      : T[keyof T] extends Function
+        ? T
+        : { -readonly [P in keyof T]: DeepWritable<T[P]> }
+
+function deepClone<T>(value: T): DeepWritable<T> {
   if (Array.isArray(value)) {
-    return value.map((v) => deepClone(v)) as T
+    return value.map((v) => deepClone(v)) as DeepWritable<T>
   }
   if (isObject(value)) {
     const cloned: Record<string, any> = {}
     for (const key in value) {
       cloned[key] = deepClone(value[key])
     }
-    return cloned as T
+    return cloned as DeepWritable<T>
   }
   if (typeof value === 'function') {
-    return value as T
+    return value as DeepWritable<T>
   }
   if (value instanceof RegExp) {
-    return structuredClone(value)
+    return structuredClone(value) as DeepWritable<T>
   }
   if (typeof value === 'object' && value != null) {
     throw new Error('Cannot deep clone non-plain object')
   }
-  return value
+  return value as DeepWritable<T>
 }
 
 type MaybeFallback<D, V> = undefined extends V ? Exclude<V, undefined> | D : V
@@ -1146,7 +1155,7 @@ function mergeWithDefaultsRecursively<
 export function mergeWithDefaults<
   D extends Record<string, any>,
   V extends Record<string, any>,
->(defaults: D, values: V): MergeWithDefaultsResult<D, V> {
+>(defaults: D, values: V): MergeWithDefaultsResult<DeepWritable<D>, V> {
   // NOTE: we need to clone the value here to avoid mutating the defaults
   const clonedDefaults = deepClone(defaults)
   return mergeWithDefaultsRecursively(clonedDefaults, values)

playground/resolve/vite.config.js

@@ -1,5 +1,5 @@
 import path from 'node:path'
-import { defineConfig, normalizePath } from 'vite'
+import { defaultClientConditions, defineConfig, normalizePath } from 'vite'
 import { a } from './config-dep.cjs'
 
 const virtualFile = '@virtual-file'
@@ -32,7 +32,7 @@ export default defineConfig({
   resolve: {
     extensions: ['.mjs', '.js', '.es', '.ts'],
     mainFields: ['browser', 'custom', 'module'],
-    conditions: ['module', 'browser', 'development|production', 'custom'],
+    conditions: [...defaultClientConditions, 'custom'],
   },
   define: {
     VITE_CONFIG_DEP_TEST: a,

playground/ssr-conditions/vite.config.js

@@ -1,11 +1,11 @@
-import { defineConfig } from 'vite'
+import { defaultServerConditions, defineConfig } from 'vite'
 
 export default defineConfig({
   ssr: {
     external: ['@vitejs/test-ssr-conditions-external'],
     noExternal: ['@vitejs/test-ssr-conditions-no-external'],
     resolve: {
-      conditions: ['module', 'node', 'development|production', 'react-server'],
+      conditions: [...defaultServerConditions, 'react-server'],
       externalConditions: ['node', 'workerd', 'react-server'],
     },
   },

playground/ssr-webworker/vite.config.js

@@ -1,4 +1,4 @@
-import { defineConfig } from 'vite'
+import { defaultClientConditions, defineConfig } from 'vite'
 
 export default defineConfig({
   build: {
@@ -14,7 +14,7 @@ export default defineConfig({
     // in the runtime, and so we can externalize it when bundling.
     external: ['node:assert'],
     resolve: {
-      conditions: ['module', 'browser', 'development|production', 'worker'],
+      conditions: [...defaultClientConditions, 'worker'],
     },
   },
   plugins: [