refactor: switch to eslint flat config (#121)

* refactor: switch to eslint flat config

* remove .eslintignore

Makefile.js

@@ -4,9 +4,7 @@
  * @copyright jQuery Foundation and other contributors, https://jquery.org/
  * MIT License
  */
-/* global echo, exec, exit, set, target */
 
-/* eslint no-console: 0*/
 //------------------------------------------------------------------------------
 // Requirements
 //------------------------------------------------------------------------------
@@ -40,15 +38,12 @@ const NODE = "node",
 
     // Utilities - intentional extra space at the end of each string
     MOCHA = `${NODE_MODULES}/mocha/bin/_mocha `,
-    ESLINT = `${NODE} ${NODE_MODULES}/eslint/bin/eslint `,
 
     // If switching back to Istanbul when may be working with ESM
     // ISTANBUL = `${NODE} ${NODE_MODULES}/istanbul/lib/cli.js `,
     C8 = `${NODE} ${NODE_MODULES}/c8/bin/c8.js`,
 
     // Files
-    MAKEFILE = "./Makefile.js",
-    JS_FILES = "lib/**/*.js",
     TEST_FILES = "tests/*.js",
     CJS_TEST_FILES = "tests/*.cjs";
 
@@ -60,39 +55,6 @@ target.all = function() {
     target.test();
 };
 
-target.lint = function() {
-    let errors = 0,
-        lastReturn;
-
-    echo("Validating Makefile.js");
-    lastReturn = exec(ESLINT + MAKEFILE);
-    if (lastReturn.code !== 0) {
-        errors++;
-    }
-
-    echo("Validating JavaScript files");
-    lastReturn = exec(ESLINT + JS_FILES);
-    if (lastReturn.code !== 0) {
-        errors++;
-    }
-
-    echo("Validating JavaScript test files");
-    lastReturn = exec(ESLINT + TEST_FILES);
-    if (lastReturn.code !== 0) {
-        errors++;
-    }
-
-    echo("Validating CJS JavaScript test files");
-    lastReturn = exec(ESLINT + CJS_TEST_FILES);
-    if (lastReturn.code !== 0) {
-        errors++;
-    }
-
-    if (errors) {
-        exit(1);
-    }
-};
-
 target.test = function() {
     let errors = 0;
     let lastReturn = exec(`${NODE} ${MOCHA} -- -R progress -c ${CJS_TEST_FILES}`);

eslint.config.js

@@ -0,0 +1,46 @@
+import eslintConfigESLint from "eslint-config-eslint";
+import globals from "globals";
+import eslintPluginChaiFriendly from "eslint-plugin-chai-friendly";
+
+export default [
+    {
+        ignores: [
+            "dist/",
+            "coverage/"
+        ]
+    },
+    ...eslintConfigESLint,
+    {
+        files: ["lib/**"],
+        rules: {
+            "no-underscore-dangle": "off"
+        }
+    },
+    {
+        files: ["tests/**"],
+        ignores: ["tests/util/**"],
+        languageOptions: {
+            globals: {
+                ...globals.mocha
+            }
+        },
+        plugins: {
+            "chai-friendly": eslintPluginChaiFriendly
+        },
+        rules: {
+            "no-unused-expressions": "off",
+            "chai-friendly/no-unused-expressions": "error"
+        }
+    },
+    {
+        files: ["Makefile.js"],
+        languageOptions: {
+            globals: {
+                ...globals.shelljs
+            }
+        },
+        rules: {
+            "no-console": "off"
+        }
+    }
+];

lib/index.js

@@ -45,7 +45,6 @@
  * The main interface is the {@link analyze} function.
  * @module escope
  */
-/* eslint no-underscore-dangle: ["error", { "allow": ["__currentScope"] }] */
 
 import assert from "assert";
 

lib/pattern-visitor.js

@@ -22,8 +22,6 @@
   THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-/* eslint-disable no-undefined */
-
 import estraverse from "estraverse";
 import esrecurse from "esrecurse";
 
@@ -38,6 +36,9 @@ function getLast(xs) {
     return xs[xs.length - 1] || null;
 }
 
+/**
+ * Visitor for destructuring patterns.
+ */
 class PatternVisitor extends esrecurse.Visitor {
     static isPattern(node) {
         const nodeType = node.type;
@@ -66,7 +67,7 @@ class PatternVisitor extends esrecurse.Visitor {
 
         this.callback(pattern, {
             topLevel: pattern === this.rootPattern,
-            rest: lastRestElement !== null && lastRestElement !== undefined && lastRestElement.argument === pattern,
+            rest: lastRestElement !== null && lastRestElement !== void 0 && lastRestElement.argument === pattern,
             assignments: this.assignments
         });
     }

lib/referencer.js

@@ -22,9 +22,6 @@
   THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-/* eslint-disable no-underscore-dangle */
-/* eslint-disable no-undefined */
-
 import estraverse from "estraverse";
 import esrecurse from "esrecurse";
 import Reference from "./reference.js";
@@ -51,7 +48,7 @@ function traverseIdentifierInPattern(options, rootPattern, referencer, callback)
     visitor.visit(rootPattern);
 
     // Process the right hand nodes recursively.
-    if (referencer !== null && referencer !== undefined) {
+    if (referencer !== null && referencer !== void 0) {
         visitor.rightHandNodes.forEach(referencer.visit, referencer);
     }
 }
@@ -62,6 +59,9 @@ function traverseIdentifierInPattern(options, rootPattern, referencer, callback)
 // FIXME: Now, we don't create module environment, because the context is
 // implementation dependent.
 
+/**
+ * Visitor for import specifiers.
+ */
 class Importer extends esrecurse.Visitor {
     constructor(declaration, referencer) {
         super(null, referencer.options);
@@ -108,7 +108,9 @@ class Importer extends esrecurse.Visitor {
     }
 }
 
-// Referencing variables and creating bindings.
+/**
+ * Referencing variables and creating bindings.
+ */
 class Referencer extends esrecurse.Visitor {
     constructor(options, scopeManager) {
         super(null, options);
@@ -432,7 +434,7 @@ class Referencer extends esrecurse.Visitor {
         this.currentScope().__referencing(node);
     }
 
-    // eslint-disable-next-line class-methods-use-this
+    // eslint-disable-next-line class-methods-use-this -- Desired as instance method
     PrivateIdentifier() {
 
         // Do nothing.
@@ -482,9 +484,9 @@ class Referencer extends esrecurse.Visitor {
         this.visitProperty(node);
     }
 
-    BreakStatement() {} // eslint-disable-line class-methods-use-this
+    BreakStatement() {} // eslint-disable-line class-methods-use-this -- Desired as instance method
 
-    ContinueStatement() {} // eslint-disable-line class-methods-use-this
+    ContinueStatement() {} // eslint-disable-line class-methods-use-this -- Desired as instance method
 
     LabeledStatement(node) {
         this.visit(node.body);
@@ -643,7 +645,7 @@ class Referencer extends esrecurse.Visitor {
         this.visit(local);
     }
 
-    MetaProperty() { // eslint-disable-line class-methods-use-this
+    MetaProperty() { // eslint-disable-line class-methods-use-this -- Desired as instance method
 
         // do nothing.
     }

lib/scope-manager.js

@@ -22,8 +22,6 @@
   THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
-/* eslint-disable no-underscore-dangle */
-
 import {
     BlockScope,
     CatchScope,
@@ -180,9 +178,9 @@ class ScopeManager {
         return null;
     }
 
-    attach() { } // eslint-disable-line class-methods-use-this
+    attach() { } // eslint-disable-line class-methods-use-this -- Desired as instance method
 
-    detach() { } // eslint-disable-line class-methods-use-this
+    detach() { } // eslint-disable-line class-methods-use-this -- Desired as instance method
 
     __nestScope(scope) {
         if (scope instanceof GlobalScope) {