microsoft · aeschli · Mar 4, 2026 · Mar 4, 2026
diff --git a/.vscode/launch.json b/.vscode/launch.json
@@ -8,12 +8,12 @@
       "runtimeArgs": [
         "--enable-source-maps",
         "--test",
-        "lib/umd/test/**/*.test.js"
+        "lib/esm/test/**/*.test.js"
       ],
       "cwd": "${workspaceRoot}",
       "sourceMaps": true,
       "outFiles": [
-        "${workspaceRoot}/lib/umd/**"
+        "${workspaceRoot}/lib/esm/**"
       ],
       "skipFiles": [
         "<node_internals>/**"

diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,11 @@
+7.0.0-next.1 / 2026-03-04
+=========================
+ * BREAKING: package is now ESM-only (`"type": "module"`) and no longer publishes `lib/umd` output
+ * BREAKING: package entrypoints now use `exports` and `types` from `lib/esm`
+ * BREAKING: runtime and test output moved to `lib/esm` and source imports use explicit `.js` extensions for NodeNext compatibility
+ * Build scripts in `build/` are now ESM
+ * `update-jsbeautify` now writes the ESM formatter source directly to `src/beautify/beautify-css.js`
+
 6.3.0 / 2022-06-24
 ================
  * new optional API `fileSystemProvider.getContent`

diff --git a/build/copy-jsbeautify.js b/build/copy-jsbeautify.js
diff --git a/build/generateData.js b/build/generateData.js
@@ -3,10 +3,14 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-const fs = require('fs')
-const path = require('path')
-const os = require('os')
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import { createRequire } from 'node:module';
+import { fileURLToPath } from 'node:url';
 
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
+const require = createRequire(import.meta.url);
 const customData = require('@vscode/web-custom-data/data/browsers.css-data.json');
 
 function toJavaScript(obj) {
@@ -21,13 +25,13 @@ const output = [
 	' *--------------------------------------------------------------------------------------------*/',
 	'// file generated from @vscode/web-custom-data NPM package',
 	'',
-	`import { ${DATA_TYPE} } from '../cssLanguageTypes';`,
+	`import { ${DATA_TYPE} } from '../cssLanguageTypes.js';`,
 	'',
 	`export const cssData : ${DATA_TYPE} = ` + toJavaScript(customData) + ';'
 ];
 
-var outputPath = path.resolve(__dirname, '../src/data/webCustomData.ts');
+const outputPath = path.resolve(__dirname, '../src/data/webCustomData.ts');
 console.log('Writing to: ' + outputPath);
-var content = output.join(os.EOL);
+const content = output.join(os.EOL);
 fs.writeFileSync(outputPath, content);
 console.log('Done');
diff --git a/build/remove-sourcemap-refs.js b/build/remove-sourcemap-refs.js
@@ -3,8 +3,11 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-const fs = require('fs');
-const path = require('path');
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 function deleteRefs(dir) {
 	const files = fs.readdirSync(dir);
@@ -27,6 +30,6 @@ function deleteRefs(dir) {
 	}
 }
 
-let location = path.join(__dirname, '..', 'lib');
+const location = path.join(__dirname, '..', 'lib');
 console.log('process ' + location);
 deleteRefs(location);
diff --git a/build/update-jsbeautify.js b/build/update-jsbeautify.js
@@ -3,86 +3,82 @@
  *  Licensed under the MIT License. See License.txt in the project root for license information.
  *--------------------------------------------------------------------------------------------*/
 
-'use strict';
+import fs from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
 
-var path = require('path');
-var fs = require('fs');
+const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
-function getVersion(moduleName) {
-    var packageJSONPath = path.join(__dirname, '..', 'node_modules', moduleName, 'package.json');
-    return readFile(packageJSONPath).then(function (content) {
-        try {
-            return JSON.parse(content).version;
-        } catch (e) {
-            return Promise.resolve(null);
-        }
-    });
+async function getVersion(moduleName) {
+    const packageJSONPath = path.join(__dirname, '..', 'node_modules', moduleName, 'package.json');
+    const content = await readFile(packageJSONPath);
+    try {
+        return JSON.parse(content).version;
+    } catch {
+        return null;
+    }
 }
 
-function readFile(path) {
-    return new Promise((s, e) => {
-        fs.readFile(path, (err, res) => {
+function readFile(filePath) {
+    return new Promise((resolve, reject) => {
+        fs.readFile(filePath, (err, res) => {
             if (err) {
-                e(err);
+                reject(err);
             } else {
-                s(res.toString());
+                resolve(res.toString());
             }
         });
     });
-
 }
 
-function update(moduleName, repoPath, dest, addHeader, patch) {
-    var contentPath = path.join(__dirname, '..', 'node_modules', moduleName, repoPath);
+async function update(moduleName, repoPath, dest, addHeader, patch) {
+    const contentPath = path.join(__dirname, '..', 'node_modules', moduleName, repoPath);
     console.log('Reading from ' + contentPath);
-    return readFile(contentPath).then(function (content) {
-        return getVersion(moduleName).then(function (version) {
-            let header = '';
-            if (addHeader) {
-                header = '// copied from js-beautify/' + repoPath + '\n';
-                if (version) {
-                    header += '// version: ' + version + '\n';
-                }
-            }
-            try {
-                if (patch) {
-                    content = patch(content);
-                }
-                fs.writeFileSync(dest, header + content);
-                if (version) {
-                    console.log('Updated ' + path.basename(dest) + ' (' + version + ')');
-                } else {
-                    console.log('Updated ' + path.basename(dest));
-                }
-            } catch (e) {
-                console.error(e);
+    try {
+        let content = await readFile(contentPath);
+        const version = await getVersion(moduleName);
+        let header = '';
+        if (addHeader) {
+            header = '// copied from js-beautify/' + repoPath + '\n';
+            if (version) {
+                header += '// version: ' + version + '\n';
             }
-        });
-
-    }, console.error);
+        }
+        if (patch) {
+            content = patch(content);
+        }
+        fs.writeFileSync(dest, header + content);
+        if (version) {
+            console.log('Updated ' + path.basename(dest) + ' (' + version + ')');
+        } else {
+            console.log('Updated ' + path.basename(dest));
+        }
+    } catch (e) {
+        console.error(e);
+    }
 }
 
-update('js-beautify', 'js/lib/beautify-css.js', './src/beautify/beautify-css.js', true);
-update('js-beautify', 'LICENSE', './src/beautify/beautify-license');
-
-// ESM version
-update('js-beautify', 'js/lib/beautify-css.js', './src/beautify/esm/beautify-css.js', true, function (contents) {
-    let topLevelFunction = '(function() {';
-    let outputVar = 'var legacy_beautify_css';
-    let footer = 'var css_beautify = legacy_beautify_css;';
-    let index1 = contents.indexOf(topLevelFunction);
-    let index2 = contents.indexOf(outputVar, index1);
-    let index3 = contents.indexOf(footer, index2);
-    if (index1 === -1) {
-        throw new Error(`Problem patching beautify.css for ESM: '${topLevelFunction}' not found.`);
-    }
-    if (index2 === -1) {
-        throw new Error(`Problem patching beautify.css for ESM: '${outputVar}' not found after '${topLevelFunction}'.`);
-    }
-    if (index3 === -1) {
-        throw new Error(`Problem patching beautify.css for ESM: '${footer}' not found after '${outputVar}'.`);
-    }
-    return contents.substring(0, index1) +
-        contents.substring(index2, index3) +
-        `\nexport var css_beautify = legacy_beautify_css;`;
-});
+await Promise.all([
+    update('js-beautify', 'LICENSE', './src/beautify/beautify-license'),
+    // Write the ESM-compatible variant directly to the main source path.
+    update('js-beautify', 'js/lib/beautify-css.js', './src/beautify/beautify-css.js', true, (contents) => {
+        const topLevelFunction = '(function() {';
+        const outputVar = 'var legacy_beautify_css';
+        const footer = 'var css_beautify = legacy_beautify_css;';
+        const index1 = contents.indexOf(topLevelFunction);
+        const index2 = contents.indexOf(outputVar, index1);
+        const index3 = contents.indexOf(footer, index2);
+        if (index1 === -1) {
+            throw new Error(`Problem patching beautify.css for ESM: '${topLevelFunction}' not found.`);
+        }
+        if (index2 === -1) {
+            throw new Error(`Problem patching beautify.css for ESM: '${outputVar}' not found after '${topLevelFunction}'.`);
+        }
+        if (index3 === -1) {
+            throw new Error(`Problem patching beautify.css for ESM: '${footer}' not found after '${outputVar}'.`);
+        }
+        return contents.substring(0, index1) +
+            contents.substring(index2, index3) +
+            '\nexport var css_beautify = legacy_beautify_css;';
+    })
+]);
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -1,10 +1,15 @@
 {
   "name": "vscode-css-languageservice",
-  "version": "6.3.10",
+  "version": "7.0.0-next.1",
   "description": "Language service for CSS, LESS and SCSS",
-  "main": "./lib/umd/cssLanguageService.js",
-  "typings": "./lib/umd/cssLanguageService",
-  "module": "./lib/esm/cssLanguageService.js",
+  "type": "module",
+  "exports": {
+    ".": {
+      "types": "./lib/esm/cssLanguageService.d.ts",
+      "import": "./lib/esm/cssLanguageService.js"
+    }
+  },
+  "types": "./lib/esm/cssLanguageService.d.ts",
   "author": "Microsoft Corporation",
   "repository": {
     "type": "git",
@@ -31,19 +36,17 @@
     "vscode-uri": "^3.1.0"
   },
   "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",
+    "prepack": "npm run clean && npm run compile && npm run test && npm run remove-sourcemap-refs",
+    "compile": "tsc -p ./src && npm run lint",
     "clean": "rimraf lib",
     "remove-sourcemap-refs": "node ./build/remove-sourcemap-refs.js",
-    "watch": "npm run copy-jsbeautify && tsc -w -p ./src",
+    "watch": "tsc -w -p ./src",
     "test": "npm run compile && npm run node-test",
-    "node-test": "node --enable-source-maps --test lib/umd/test/**/*.test.js",
-    "coverage": "npm run compile && npx nyc --reporter=html --reporter=text node --test lib/umd/test/**/*.test.js",
+    "node-test": "node --enable-source-maps --test lib/esm/test/**/*.test.js",
+    "coverage": "npm run compile && npx nyc --reporter=html --reporter=text node --test lib/esm/test/**/*.test.js",
     "lint": "eslint src/**/*.ts",
     "update-data": "npm install @vscode/web-custom-data -D && node ./build/generateData.js",
     "install-types-next": "npm install vscode-languageserver-types@next -f -S && npm install vscode-languageserver-textdocument@next -f -S",
-    "copy-jsbeautify": "node ./build/copy-jsbeautify.js",
     "update-jsbeautify": "npm install js-beautify && node ./build/update-jsbeautify.js",
     "update-jsbeautify-next": "npm install js-beautify@next && node ./build/update-jsbeautify.js"
   }

diff --git a/src/beautify/beautify-css.js b/src/beautify/beautify-css.js
@@ -64,9 +64,6 @@
 // http://www.w3.org/TR/CSS21/syndata.html#tokenization
 // http://www.w3.org/TR/css3-syntax/
 
-(function() {
-
-/* GENERATED_BUILD_OUTPUT */
 var legacy_beautify_css;
 /******/ (function() { // webpackBootstrap
 /******/ 	"use strict";
@@ -1671,25 +1668,5 @@ module.exports.Options = Options;
 /******/ 	
 /******/ })()
 ;
-var css_beautify = legacy_beautify_css;
-/* Footer */
-if (typeof define === "function" && define.amd) {
-    // Add support for AMD ( https://github.com/amdjs/amdjs-api/wiki/AMD#defineamd-property- )
-    define([], function() {
-        return {
-            css_beautify: css_beautify
-        };
-    });
-} else if (typeof exports !== "undefined") {
-    // Add support for CommonJS. Just put this file somewhere on your require.paths
-    // and you will be able to `var html_beautify = require("beautify").html_beautify`.
-    exports.css_beautify = css_beautify;
-} else if (typeof window !== "undefined") {
-    // If we're running a web page and don't have either of the above, add our one global
-    window.css_beautify = css_beautify;
-} else if (typeof global !== "undefined") {
-    // If we don't even have window, try global.
-    global.css_beautify = css_beautify;
-}
 
-}());
+export var css_beautify = legacy_beautify_css;