- Enhancement: Provide ESM distribution pointed to by module

- Refactoring: Switch to ESM source, using Rollup + Babel/Terser
- Refactoring: Further ES6 class

Author: brettz9

.gitignore

@@ -12,3 +12,5 @@ coverage/
 
 npm-debug.log
 .vimrc.local
+
+dist

package.json

@@ -3,7 +3,8 @@
   "description": "ECMAScript JS AST traversal functions",
   "homepage": "https://github.com/estools/estraverse",
   "bugs": "https://github.com/estools/estraverse/issues",
-  "main": "estraverse.js",
+  "main": "dist/estraverse.min.js",
+  "module": "dist/estraverse.esm.min.js",
   "version": "5.3.0",
   "engines": {
     "node": ">=4.0"
@@ -32,12 +33,15 @@
     "@babel/core": "^7.17.5",
     "@babel/preset-env": "^7.16.11",
     "@babel/register": "^7.17.0",
+    "@rollup/plugin-babel": "^5.0.0",
     "chai": "^4.3.6",
     "eslint": "^6.8.0",
     "espree": "^9.3.1",
     "esprima": "^4.0.1",
     "mocha": "^9.2.1",
-    "nyc": "^15.1.0"
+    "nyc": "^15.1.0",
+    "rollup": "^2.7.3",
+    "rollup-plugin-terser": "^5.3.0"
   },
   "license": "BSD-2-Clause",
   "nyc": {
@@ -54,6 +58,7 @@
     ]
   },
   "scripts": {
+    "build": "rollup -c",
     "test": "npm run lint && npm run unit-test",
     "lint": "eslint .",
     "unit-test": "nyc mocha --require chai/register-expect.js --require @babel/register"

rollup.config.js

@@ -0,0 +1,45 @@
+import { terser } from 'rollup-plugin-terser';
+
+import babel from '@rollup/plugin-babel';
+
+/**
+ * @external RollupConfig
+ * @type {PlainObject}
+ * @see {@link https://rollupjs.org/guide/en#big-list-of-options}
+ */
+
+/**
+ * @param {PlainObject} [config= {}]
+ * @param {boolean} [config.minifying=false]
+ * @param {string} [config.format='umd']
+ * @returns {external:RollupConfig}
+ */
+function getRollupObject ({ minifying, format = 'umd' } = {}) {
+    const nonMinified = {
+        input: 'src/estraverse.js',
+        output: {
+            format,
+            sourcemap: minifying,
+            file: `dist/estraverse${
+                format === 'umd' ? '' : `.${format}`
+            }${minifying ? '.min' : ''}.js`,
+            name: 'estraverse'
+        },
+        plugins: [
+            babel({
+                babelHelpers: 'bundled'
+            })
+        ]
+    };
+    if (minifying) {
+        nonMinified.plugins.push(terser());
+    }
+    return nonMinified;
+}
+
+export default [
+    getRollupObject({ minifying: true, format: 'umd' }),
+    getRollupObject({ minifying: false, format: 'umd' }),
+    getRollupObject({ minifying: true, format: 'esm' }),
+    getRollupObject({ minifying: false, format: 'esm' })
+];