- Enhancement: Add ESM distribution, with module property in package.json

- Refactoring: Add Rollup/Babel/Terser
- Build: Have generator file produce consumable source files directly rather than logging to console
- Linting: Switch from JSHint to ESLint (using rules, e.g., `indent` and `prefer-const`, in place on other estools project)
- Testing: Convert coffeescript test files to ES6
- Testing: Add nyc
- Testing: Check unmatched high surrogates and full coverage for AST
    expressions (further true `isExpression` and `isStatement`'s and
    false `isProblematicIfStatement`), bringing to 100% coverage
- Travis: Drop previous versions for 10, 12, 14

Author: brettz9

.babelrc.json

@@ -0,0 +1,5 @@
+{
+  "presets": [
+    ["@babel/preset-env"]
+  ]
+}

.eslintignore

@@ -0,0 +1,8 @@
+node_modules
+dist
+
+!.eslintrc.js
+coverage
+
+src/es5-identifier.js
+src/es6-identifier.js

.eslintrc.js

@@ -0,0 +1,48 @@
+'use strict';
+module.exports = {
+    env: {
+        browser: true,
+        commonjs: true,
+        es6: true,
+        node: true
+    },
+    extends: 'eslint:recommended',
+    globals: {
+        Atomics: 'readonly',
+        SharedArrayBuffer: 'readonly'
+    },
+    overrides: [{
+        files: '.eslintrc.js',
+        parserOptions: {
+            sourceType: 'script'
+        },
+        rules: {
+            strict: 'error'
+        }
+    }, {
+        files: 'test/**',
+        globals: {
+            expect: true
+        },
+        env: {
+            mocha: true
+        }
+    }],
+    parserOptions: {
+        sourceType: 'module',
+        ecmaVersion: 2018
+    },
+    rules: {
+        semi: ['error'],
+        indent: ['error', 4, { SwitchCase: 1 }],
+        'prefer-const': ['error'],
+        'no-var': ['error'],
+        'prefer-destructuring': ['error'],
+        'object-shorthand': ['error'],
+        'object-curly-spacing': ['error', 'always'],
+        quotes: ['error', 'single'],
+        'quote-props': ['error', 'as-needed'],
+        'brace-style': ['error', '1tbs', { allowSingleLine: true }],
+        'prefer-template': ['error']
+    }
+};

.gitignore

@@ -1 +1,3 @@
 node_modules
+dist
+coverage

.jshintrc

@@ -1,8 +1,5 @@
 language: node_js
 node_js:
-    - "0.10"
-    - "0.11"
-
-matrix:
-    allow_failures:
-        - node_js: "0.11"
+  - 10
+  - 12
+  - 14

.travis.yml

@@ -3,18 +3,19 @@
   "description": "utility box for ECMAScript language tools",
   "homepage": "https://github.com/estools/esutils",
   "bugs": "https://github.com/estools/esutils/issues",
-  "main": "lib/utils.js",
+  "main": "dist/esutils.min.js",
+  "module": "dist/esutils.esm.min.js",
   "version": "2.0.4-dev",
   "engines": {
     "node": ">=0.10.0"
   },
   "directories": {
-    "lib": "./lib"
+    "lib": "./dist"
   },
   "files": [
     "LICENSE.BSD",
     "README.md",
-    "lib"
+    "dist"
   ],
   "keywords": [
     "ecmascript"
@@ -33,18 +34,39 @@
   },
   "dependencies": {},
   "devDependencies": {
+    "@babel/core": "^7.9.0",
+    "@babel/preset-env": "^7.9.5",
+    "@babel/register": "^7.9.0",
+    "@rollup/plugin-babel": "^5.0.0",
     "chai": "~4.2.0",
     "coffeescript": "^2.5.1",
-    "jshint": "2.11.0",
+    "eslint": "^6.8.0",
     "mocha": "~7.1.2",
+    "nyc": "^15.0.1",
     "regenerate": "~1.4.0",
+    "rollup": "^2.7.3",
+    "rollup-plugin-terser": "^5.3.0",
     "unicode-13.0.0": "^0.8.0"
   },
   "license": "BSD-2-Clause",
+  "nyc": {
+    "branches": 100,
+    "lines": 100,
+    "functions": 100,
+    "statements": 100,
+    "reporter": [
+      "html",
+      "text"
+    ],
+    "exclude": [
+      "test"
+    ]
+  },
   "scripts": {
+    "build": "rollup -c",
     "test": "npm run lint && npm run unit-test",
-    "lint": "jshint lib/*.js",
-    "unit-test": "mocha --require chai/register-expect --require coffeescript/register test/**",
+    "lint": "eslint .",
+    "unit-test": "nyc mocha --require @babel/register --require chai/register-expect --require coffeescript/register test/**",
     "generate-regex": "node tools/generate-identifier-regex.js"
   }
 }

lib/ast.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/utils.js',
+        output: {
+            format,
+            sourcemap: minifying,
+            file: `dist/esutils${
+                format === 'umd' ? '' : `.${format}`
+            }${minifying ? '.min' : ''}.js`,
+            name: 'esutils'
+        },
+        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' })
+];