fix: merge options correctly

package.json

@@ -61,6 +61,7 @@
   "devDependencies": {
     "@types/node": "^22.10.4",
     "@vida0905/eslint-config": "^1.2.0",
+    "es-toolkit": "^1.31.0",
     "eslint": "^9.17.0",
     "eslint-vitest-rule-tester": "^0.7.1",
     "lint-staged": "^15.3.0",

src/index.ts

@@ -6,6 +6,7 @@ import { normalizeOptions } from './normalizeOptions'
 import { hashObject } from './utils'
 
 export { transformViteConfig } from './bundler/vite'
+export { mergeOptions } from './normalizeOptions'
 
 let cachedOptionsHash: string | undefined
 let cachedResolver: ResolverFactory | undefined

src/normalizeOptions.ts

@@ -1,5 +1,6 @@
 import type { OxcResolverOptions } from './typings'
 import { cwd } from 'node:process'
+import { isPlainObject, mergeWith } from 'es-toolkit'
 import { getBundlerConfig } from './bundler'
 import { detectFile } from './utils'
 
@@ -68,6 +69,20 @@ const defaultOptions: OxcResolverOptions = {
   roots: [cwd()],
 }
 
+export function mergeOptions(a?: OxcResolverOptions | null, b?: OxcResolverOptions | null): OxcResolverOptions {
+  a ??= {}
+  b ??= {}
+
+  function mergeFunc(objVal: any, srcVal: any) {
+    if (Array.isArray(objVal) || Array.isArray(srcVal)) {
+      return objVal.concat(srcVal)
+    } else if (isPlainObject(objVal) && isPlainObject(srcVal)) {
+      return mergeWith(objVal, srcVal, mergeFunc)
+    }
+  }
+  return mergeWith(a, b, mergeFunc)
+}
+
 export function normalizeOptions(options: OxcResolverOptions | null = {}): OxcResolverOptions {
   if (!options?.tsconfig) {
     const configFile = detectFile(['tsconfig.json', 'jsconfig.json'])
@@ -81,7 +96,9 @@ export function normalizeOptions(options: OxcResolverOptions | null = {}): OxcRe
 
   return {
     ...defaultOptions,
-    ...getBundlerConfig(options?.bundlerConfig),
-    ...options,
+    ...mergeOptions(
+      options,
+      getBundlerConfig(options?.bundlerConfig),
+    ),
   }
 }