Dual-package ESM and CJS (#7)

Postcss now supports importing plugins as ESM, so this will dual-publish ESM and CJS using TSUP.

.gitignore

@@ -5,5 +5,4 @@ yarn-error.log
 coverage/
 
 # build products
-index.js
-index.d.ts
+dist/*

eslint.config.mjs

@@ -14,7 +14,7 @@ export default tseslint.config(
   eslint.configs.recommended,
   ...tseslint.configs.recommended,
   {
-    ignores: ["coverage/*", "index.js", "index.test.mjs", "index.d.ts"],
+    ignores: ["coverage/*", "dist"],
   },
   {
     languageOptions: {

package.json

@@ -9,7 +9,7 @@
     "postcss-assign-layer"
   ],
   "scripts": {
-    "build": "tsc -p tsconfig.json",
+    "build": "tsup src/index.ts --format esm,cjs --dts",
     "test": "vitest run --coverage && eslint .",
     "test:watch": "vitest",
     "prepublishOnly": "pnpm build && pnpm test"
@@ -22,9 +22,20 @@
   },
   "homepage": "https://github.com/DefinedNet/postcss-assign-layer#readme",
   "files": [
-    "index.js",
-    "index.d.ts"
+    "dist"
   ],
+  "exports": {
+    ".": {
+      "types": {
+        "import": "./dist/index.d.mts",
+        "require": "./dist/index.d.ts"
+      },
+      "import": "./dist/index.mjs",
+      "require": "./dist/index.js"
+    },
+    "./package.json": "./package.json"
+  },
+  "main": "dist/index.js",
   "engines": {
     "node": ">=12.0.0"
   },
@@ -43,6 +54,7 @@
     "eslint-plugin-no-only-tests": "^3.1.0",
     "postcss": "^8.3.11",
     "prettier": "^2.6.2",
+    "tsup": "^8.0.2",
     "typescript": "^5.4.2",
     "typescript-eslint": "^7.3.1",
     "vite": "^4.0.0",