feat: allow regular expressions in externals array

src/builder/rollup.ts

@@ -10,7 +10,7 @@ import dts from 'rollup-plugin-dts'
 import replace from '@rollup/plugin-replace'
 import { resolve, dirname, normalize, extname } from 'pathe'
 import { resolvePath, resolveModuleExportNames } from 'mlly'
-import { getpkg, tryResolve, warn } from '../utils'
+import { arrayIncludes, getpkg, tryResolve, warn } from '../utils'
 import type { BuildContext } from '../types'
 import { esbuild } from './plugins/esbuild'
 import { JSONPlugin } from './plugins/json'
@@ -168,7 +168,7 @@ export function getRollupOptions (ctx: BuildContext): RollupOptions {
 
     external (id) {
       const pkg = getpkg(id)
-      const isExplicitExternal = ctx.options.externals.includes(pkg)
+      const isExplicitExternal = arrayIncludes(ctx.options.externals, pkg)
       if (isExplicitExternal) {
         return true
       }

src/types.ts

@@ -61,7 +61,7 @@ export interface BuildOptions {
   declaration?: boolean
   outDir: string
   stub: boolean
-  externals: string[]
+  externals: (string|RegExp)[]
   dependencies: string[]
   peerDependencies: string[]
   devDependencies: string[]

src/utils.ts

@@ -142,3 +142,7 @@ export function extractExportFilenames (exports: PackageJson['exports'], conditi
         : extractExportFilenames(exports, [...conditions, condition])
     )
 }
+
+export function arrayIncludes (arr: (string|RegExp)[], searchElement: string) {
+  return arr.some(entry => entry instanceof RegExp ? entry.test(searchElement) : entry === searchElement)
+}

src/validate.ts

@@ -2,7 +2,7 @@ import { existsSync } from 'fs'
 import chalk from 'chalk'
 import { resolve } from 'pathe'
 import { PackageJson } from 'pkg-types'
-import { extractExportFilenames, getpkg, warn } from './utils'
+import { extractExportFilenames, getpkg, arrayIncludes, warn } from './utils'
 import { BuildContext } from './types'
 
 export function validateDependencies (ctx: BuildContext) {
@@ -20,7 +20,7 @@ export function validateDependencies (ctx: BuildContext) {
   }
   for (const id of usedDependencies) {
     if (
-      !ctx.options.externals.includes(id) &&
+      !arrayIncludes(ctx.options.externals, id) &&
       !id.startsWith('chunks/') &&
       !ctx.options.dependencies.includes(getpkg(id)) &&
       !ctx.options.peerDependencies.includes(getpkg(id))

test/utils.test.ts

@@ -1,5 +1,5 @@
 import { describe, it, expect } from 'vitest'
-import { extractExportFilenames, inferExportType } from '../src/utils'
+import { extractExportFilenames, inferExportType, arrayIncludes } from '../src/utils'
 
 describe('inferExportType', () => {
   it('infers export type by condition', () => {
@@ -26,3 +26,14 @@ describe('extractExportFilenames', () => {
     expect(extractExportFilenames({ require: { node: 'test', other: { import: 'this', require: 'that' } } })).to.deep.equal([{ file: 'test', type: 'cjs' }, { file: 'this', type: 'esm' }, { file: 'that', type: 'cjs' }])
   })
 })
+
+describe('arrayIncludes', () => {
+  it('handles strings', () => {
+    expect(arrayIncludes(['test1', 'test2'], 'test1')).to.eq(true)
+    expect(arrayIncludes(['test1', 'test2'], 'test3')).to.eq(false)
+  })
+  it('handles regular expressions', () => {
+    expect(arrayIncludes([/t1$/, 'test2'], 'test1')).to.eq(true)
+    expect(arrayIncludes([/t3$/, 'test2'], 'test1')).to.eq(false)
+  })
+})