refactor: switch to eslint flat config (#577)

* refactor: switch to eslint flat config

* rename eslintConfigESLint variable

.gitignore

@@ -6,6 +6,7 @@ dist
 npm-debug.log
 _test.js
 .idea
+.vscode
 .nyc_output
 .eslint-release-info.json
 yarn.lock

eslint.config.js

@@ -0,0 +1,54 @@
+import eslintConfigESLint from "eslint-config-eslint";
+import nodeRecommendedModule from "eslint-plugin-n/configs/recommended-module.js";
+import nodeRecommendedScript from "eslint-plugin-n/configs/recommended-script.js";
+import globals from "globals";
+
+export default [
+    {
+        ignores: [
+            "tests/fixtures/",
+            "dist/",
+            "coverage/",
+            "tools/create-test-example.js"
+        ]
+    },
+
+    // eslintConfigESLint[3] is eslint-plugin-n's recommended-script config
+    ...eslintConfigESLint.slice(0, 3),
+    {
+        files: ["**/*.js"],
+        ...nodeRecommendedModule
+    },
+    {
+        files: ["**/*.cjs"],
+        ...nodeRecommendedScript
+    },
+    ...eslintConfigESLint.slice(4),
+
+    {
+        settings: {
+            jsdoc: {
+                mode: "typescript"
+            }
+        }
+    },
+    {
+        files: ["tests/lib/**"],
+        languageOptions: {
+            globals: {
+                ...globals.mocha
+            }
+        }
+    },
+    {
+        files: ["tools/**"],
+        rules: {
+            "no-console": "off",
+            "n/no-process-exit": "off",
+            "n/no-unsupported-features/es-syntax": ["error", {
+                version: ">=16.0.0",
+                ignores: ["modules"]
+            }]
+        }
+    }
+];

espree.js

@@ -1,3 +1,5 @@
+/* eslint-disable jsdoc/no-multi-asterisks -- needed to preserve original formatting of licences */
+
 /**
  * @fileoverview Main Espree file that converts Acorn into Esprima output.
  *
@@ -54,7 +56,8 @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
-/* eslint no-undefined:0, no-use-before-define: 0 */
+
+/* eslint-enable jsdoc/no-multi-asterisks -- needed to preserve original formatting of licences */
 
 import * as acorn from "acorn";
 import jsx from "acorn-jsx";
@@ -111,7 +114,7 @@ export function tokenize(code, options) {
 
     // Ensure to collect tokens.
     if (!options || options.tokens !== true) {
-        options = Object.assign({}, options, { tokens: true }); // eslint-disable-line no-param-reassign
+        options = Object.assign({}, options, { tokens: true }); // eslint-disable-line no-param-reassign -- stylistic choice
     }
 
     return new Parser(options, code).tokenize();

lib/espree.js

@@ -1,4 +1,5 @@
-/* eslint-disable no-param-reassign*/
+/* eslint no-param-reassign: 0 -- stylistic choice */
+
 import TokenTranslator from "./token-translator.js";
 import { normalizeOptions } from "./options.js";
 
@@ -109,7 +110,7 @@ export default () => Parser => {
                 allowReturnOutsideFunction: options.allowReturnOutsideFunction,
 
                 // Collect tokens
-                onToken: token => {
+                onToken(token) {
                     if (tokenTranslator) {
 
                         // Use `tokens`, `ecmaVersion`, and `jsxAttrValueToken` in the state.
@@ -121,7 +122,7 @@ export default () => Parser => {
                 },
 
                 // Collect comments
-                onComment: (block, text, start, end, startLoc, endLoc) => {
+                onComment(block, text, start, end, startLoc, endLoc) {
                     if (state.comments) {
                         const comment = convertAcornCommentToEsprimaComment(block, text, start, end, startLoc, endLoc, code);
 
@@ -314,7 +315,7 @@ export default () => Parser => {
         * on extra so that when tokens are converted, the next token will be switched
         * to JSXText via onToken.
         */
-        jsx_readString(quote) { // eslint-disable-line camelcase
+        jsx_readString(quote) { // eslint-disable-line camelcase -- required by API
             const result = super.jsx_readString(quote);
 
             if (this.type === tokTypes.string) {

lib/token-translator.js

@@ -2,7 +2,6 @@
  * @fileoverview Translates tokens between Acorn format and Esprima format.
  * @author Nicholas C. Zakas
  */
-/* eslint no-underscore-dangle: 0 */
 
 //------------------------------------------------------------------------------
 // Requirements
@@ -180,8 +179,7 @@ TokenTranslator.prototype = {
      */
     onToken(token, extra) {
 
-        const that = this,
-            tt = this._acornTokTypes,
+        const tt = this._acornTokTypes,
             tokens = extra.tokens,
             templateTokens = this._tokens;
 
@@ -191,10 +189,10 @@ TokenTranslator.prototype = {
          * @returns {void}
          * @private
          */
-        function translateTemplateTokens() {
-            tokens.push(convertTemplatePart(that._tokens, that._code));
-            that._tokens = [];
-        }
+        const translateTemplateTokens = () => {
+            tokens.push(convertTemplatePart(this._tokens, this._code));
+            this._tokens = [];
+        };
 
         if (token.type === tt.eof) {
 

package.json

@@ -42,12 +42,12 @@
     "@rollup/plugin-node-resolve": "^11.2.0",
     "c8": "^7.11.0",
     "chai": "^4.3.6",
-    "eslint": "^8.13.0",
-    "eslint-config-eslint": "^7.0.0",
-    "eslint-plugin-jsdoc": "^39.2.4",
-    "eslint-plugin-node": "^11.1.0",
+    "eslint": "^8.44.0",
+    "eslint-config-eslint": "^8.0.0",
+    "eslint-plugin-n": "^16.0.0",
     "eslint-release": "^3.2.0",
     "esprima-fb": "^8001.2001.0-dev-harmony-fb",
+    "globals": "^13.20.0",
     "lint-staged": "^13.2.0",
     "mocha": "^9.2.2",
     "npm-run-all": "^4.1.5",
@@ -71,7 +71,7 @@
     "unit:esm": "c8 mocha --color --reporter progress --timeout 30000 'tests/lib/**/*.js'",
     "unit:cjs": "mocha --color --reporter progress --timeout 30000 tests/lib/commonjs.cjs",
     "test": "npm-run-all -p unit lint",
-    "lint": "eslint .",
+    "lint": "eslint .  --report-unused-disable-directives",
     "fixlint": "npm run lint -- --fix",
     "build": "rollup -c rollup.config.js",
     "build:debug": "npm run build -- -m",

tests/lib/acorn-after-espree.js

@@ -19,7 +19,6 @@ describe("acorn", () => {
     it("acorn.parse() should work after espree was loaded.", async () => {
         const before = acorn.parse("var foo = bar /*world*/;", { ecmaVersion: 5 });
 
-        // eslint-disable-next-line node/no-unsupported-features/es-syntax
         await import("../../espree.js");
 
         const after = acorn.parse("var foo = bar /*world*/;", { ecmaVersion: 5 });

tests/lib/commonjs.cjs

@@ -3,7 +3,6 @@
  * @author Mike Reinstein
  */
 
-// eslint-disable-next-line strict
 "use strict";
 
 //------------------------------------------------------------------------------

tests/lib/conditional-regex-value.js

@@ -16,8 +16,7 @@ export default function(literalNode) {
     if (literalNode.regex) {
         try {
             literalNode.value = new RegExp(literalNode.regex.pattern, literalNode.regex.flags);
-            /* eslint-disable no-unused-vars */
-        } catch (e) {
+        } catch {
             literalNode.value = null;
         }
     }

tests/lib/ecma-features.js

@@ -15,7 +15,7 @@ import { fileURLToPath, pathToFileURL } from "url";
 import tester from "./tester.js";
 
 
-// eslint-disable-next-line no-underscore-dangle
+// eslint-disable-next-line no-underscore-dangle -- Conventional
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 
@@ -68,7 +68,6 @@ describe("ecmaFeatures", () => {
             it(`should parse correctly when ${feature} is ${isPermissive}`, async () => {
                 config.ecmaFeatures[feature] = isPermissive;
 
-                // eslint-disable-next-line node/no-unsupported-features/es-syntax
                 const expected = await import(`${pathToFileURL(path.resolve(__dirname, "../../", FIXTURES_DIR, filename)).href}.result.js`);
 
                 tester.assertMatches(code, config, expected.default);

tests/lib/ecma-version.js

@@ -16,7 +16,7 @@ import assert from "assert";
 import { fileURLToPath, pathToFileURL } from "url";
 
 
-// eslint-disable-next-line no-underscore-dangle
+// eslint-disable-next-line no-underscore-dangle -- Conventional
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 
@@ -73,7 +73,6 @@ describe("ecmaVersion", () => {
                     }
 
                     const absolutePath = path.resolve(__dirname, FIXTURES_DIR, filename.slice(1));
-                    // eslint-disable-next-line node/no-unsupported-features/es-syntax
                     const expected = await import(`${pathToFileURL(absolutePath).href}.result.js`);
 
                     tester.assertMatches(code, config, expected.default);
@@ -97,10 +96,8 @@ describe("ecmaVersion", () => {
                     let expected;
 
                     try {
-                        // eslint-disable-next-line node/no-unsupported-features/es-syntax
                         expected = await import(`${pathToFileURL(absolutePath).href}.module-result.js`);
                     } catch {
-                        // eslint-disable-next-line node/no-unsupported-features/es-syntax
                         expected = await import(`${pathToFileURL(absolutePath).href}.result.js`);
                     }
 

tests/lib/libraries.js

@@ -14,7 +14,7 @@ import * as espree from "../../espree.js";
 import assert from "assert";
 import { fileURLToPath } from "url";
 
-// eslint-disable-next-line no-underscore-dangle
+// eslint-disable-next-line no-underscore-dangle -- Conventional
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 
 

tests/lib/tester-test.js

@@ -42,9 +42,9 @@ describe("Tester", () => {
 
         it("should keep RegExp objects", () => {
             assert.deepStrictEqual(
-                // eslint-disable-next-line require-unicode-regexp
+                // eslint-disable-next-line require-unicode-regexp -- non-unicode regexp is needed for the test
                 getRaw({ value: /foo/ }),
-                // eslint-disable-next-line require-unicode-regexp
+                // eslint-disable-next-line require-unicode-regexp -- non-unicode regexp is needed for the test
                 { value: /foo/ }
             );
             assert.deepStrictEqual(
@@ -74,7 +74,7 @@ describe("Tester", () => {
         function test(ast) {
             const code = getAstCode(ast);
 
-            // eslint-disable-next-line no-new-func
+            // eslint-disable-next-line no-new-func -- it's okay to eval code in tests
             return Function(`return ${code};`)();
         }
 
@@ -115,9 +115,9 @@ describe("Tester", () => {
 
         it("should keep RegExp objects", () => {
             assert.deepStrictEqual(
-                // eslint-disable-next-line require-unicode-regexp
+                // eslint-disable-next-line require-unicode-regexp -- non-unicode regexp is needed for the test
                 test({ value: /foo/ }),
-                // eslint-disable-next-line require-unicode-regexp
+                // eslint-disable-next-line require-unicode-regexp -- non-unicode regexp is needed for the test
                 { value: /foo/ }
             );
             assert.deepStrictEqual(

tests/lib/tester.js

@@ -36,13 +36,14 @@ const ReplacedStringLiteralPattern = new RegExp(
  * @returns {any} If `value` parameter is a value JSON cannot handle, this
  * function returns a string value. If `key` parameter is `"start"` or `"end"`,
  * returns `undefined`. Otherwise, returns `value` parameter as is.
+ * @throws {Error} If `value` is undefined
  * @private
  */
 function replaceToSaveNonJSONValues(key, value) {
 
     // Remove `start` and `end` properties because of non-standard.
     if ((key === "start" || key === "end") && typeof value === "number") {
-        return undefined; // eslint-disable-line no-undefined
+        return void 0;
     }
 
     // Save the values JSON cannot handle.
@@ -155,6 +156,7 @@ function getAstCode(ast) {
  * @param {Object} parserOptions The parser options to parse.
  * @param {Object} [options] The options.
  * @param {boolean} [options.rethrowSyntaxError = false] The flag to rethrow syntax errors.
+ * @throws {Error} If options.rethrowSyntaxError = true, rethrows syntax errors
  * @returns {Object} The normalized AST.
  */
 function getExpectedResult(jsCodeText, parserOptions, { rethrowSyntaxError = false } = {}) {

tools/create-test.js

@@ -1,4 +1,3 @@
-/* eslint-disable node/no-process-exit */
 /**
  * @fileoverview A simple script to help generate test cases
  * @author Nicholas C. Zakas

tools/sync-docs.js

@@ -2,15 +2,15 @@
  * @fileoverview Build file
  * @author nzakas
  */
-/* global cp, echo, rm */
 
-/* eslint no-console: 0*/
 //------------------------------------------------------------------------------
 // Requirements
 //------------------------------------------------------------------------------
 
 import "shelljs/make.js";
 
+/* global cp, echo, rm -- declared in `shelljs/make.js` */
+
 
 //------------------------------------------------------------------------------
 // Data

tools/update-ecma-version-tests.js

@@ -1,12 +1,12 @@
 /**
  * @fileoverview Generate `<test-name>.result.js` from `<test-name>.src.js` in
  *               `tests/fixtures/ecma-version/<number>/**` directory.
- * @author Nicholas C. Zakas
- * @author Toru Nagashima
  *
  * Usage:
  *      node tools/update-ecma-version-tests.js <number>
  *
+ * @author Nicholas C. Zakas
+ * @author Toru Nagashima
  */
 
 //------------------------------------------------------------------------------