use exports

build/fix-esm.js

@@ -0,0 +1,12 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+'use strict';
+//@ts-check
+
+const fs = require('fs');
+
+const pkg = { type: 'module' };
+
+fs.writeFileSync('lib/esm/package.json', JSON.stringify(pkg, undefined, 2) + '\n');

package.json

@@ -4,7 +4,12 @@
   "description": "Language service for CSS, LESS and SCSS",
   "main": "./lib/umd/cssLanguageService.js",
   "typings": "./lib/umd/cssLanguageService",
-  "module": "./lib/esm/cssLanguageService.js",
+  "exports": {
+		".": {
+			"import": "./lib/esm/cssLanguageService.js",
+			"default": "./lib/umd/cssLanguageService.js"
+		}
+	},
   "author": "Microsoft Corporation",
   "repository": {
     "type": "git",
@@ -36,7 +41,7 @@
   "scripts": {
     "prepack": "npm run clean && npm run compile-esm && npm run test && npm run remove-sourcemap-refs",
     "compile": "tsc -p ./src && npm run copy-jsbeautify && npm run lint ",
-    "compile-esm": "tsc -p ./src/tsconfig.esm.json",
+    "compile-esm": "tsc -p ./src/tsconfig.esm.json && node ./build/fix-esm.js",
     "clean": "rimraf lib",
     "remove-sourcemap-refs": "node ./build/remove-sourcemap-refs.js",
     "watch": "npm run copy-jsbeautify && tsc -w -p ./src",

src/tsconfig.esm.json

@@ -1,7 +1,7 @@
 {
 	"compilerOptions": {
-		"target": "es2020",
-		"module": "es6",
+		"target": "es6",
+		"module": "esnext",
 		"moduleResolution": "node",
 		"sourceMap": true,
 		"declaration": true,