fix: use es2015 for legacy build (#36)

Co-authored-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

.changeset/selfish-days-love.md

@@ -0,0 +1,5 @@
+---
+"exceptionally": patch
+---
+
+use `es2015` as target fo legacy build

.size-limit.cjs

@@ -7,11 +7,11 @@ const config = [
 	},
 	{
 		path: 'lib/index.cjs',
-		limit: '226 b',
+		limit: '192 b',
 	},
 	{
 		path: 'lib/index.global.js',
-		limit: '208 b',
+		limit: '176 b',
 	},
 ]
 

CHANGELOG.md

@@ -7,6 +7,12 @@
 - e97b58d: upgrade to TypeScript 5
 - e97b58d: improve type definition for `processInParallel`
 
+## 2.8.1
+
+### Patch Changes
+
+- 1c5de55: use `es2015` as target fo legacy build
+
 ## 2.8.0
 
 ### Minor Changes

package.json

@@ -6,7 +6,7 @@
 		"---- DEV -----------------------------------------------------------------------------": "",
 		"dev": "tsup --watch",
 		"---- BUILD ---------------------------------------------------------------------------": "",
-		"build": "tsup",
+		"build": "tsup && tsup --config tsup-legacy.config.ts",
 		"release": "pnpm build && npm publish",
 		"---- TEST ----------------------------------------------------------------------------": "",
 		"test": "pnpm tsc && pnpm vitest",

tsup-legacy.config.ts

@@ -0,0 +1,8 @@
+import { defineConfig } from 'tsup'
+import { getTsupConfig } from './tsup.config.js'
+
+export default defineConfig(({ watch }) => ({
+	...getTsupConfig(watch),
+	entry: ['src/legacy.ts'],
+	target: 'es2015',
+}))

tsup.config.ts

@@ -1,12 +1,17 @@
-import { defineConfig } from 'tsup'
+import { defineConfig, type Options } from 'tsup'
+
+export const getTsupConfig = (watch: Options['watch']) =>
+	({
+		outDir: 'lib',
+		format: ['esm', 'cjs', 'iife'],
+		dts: true,
+		treeshake: true,
+		sourcemap: !!watch,
+		minify: !watch,
+	}) satisfies Options
 
 export default defineConfig(({ watch }) => ({
-	entry: ['src/index.ts', 'src/assert/index.ts', 'src/utils/index.ts', 'src/legacy.ts'],
-	outDir: 'lib',
-	format: ['esm', 'cjs', 'iife'],
-	dts: true,
-	treeshake: true,
-	sourcemap: !!watch,
+	...getTsupConfig(watch),
 	clean: true,
-	minify: !watch,
+	entry: ['src/index.ts', 'src/assert/index.ts', 'src/utils/index.ts'],
 }))