chore: Use eslint v9 and flat config (#738)

This PR changes to use ESLint v9.

Author: ota-meshi

.eslintignore

@@ -39,13 +39,8 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        eslint: [7, 8]
+        eslint: [7, 8, 9]
         node: [20]
-        include:
-          # On next ESLint version
-          - eslint: ^9.0.0-0
-            node: 20
-            os: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -58,7 +53,7 @@ jobs:
         run: |+
           pnpm install -D eslint@${{ matrix.eslint }}
           rm -rf node_modules
-        if: matrix.eslint != 8
+        if: matrix.eslint != 9
       - name: Install Packages
         run: pnpm install
       - name: Test
@@ -69,7 +64,16 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        node: [16, 17, 18, 20]
+        eslint: [9]
+        node: [18, 20]
+        include:
+          # On old Node.js version
+          - eslint: 8
+            node: 16
+            os: ubuntu-latest
+          - eslint: 8
+            node: 17
+            os: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v4
@@ -82,6 +86,10 @@ jobs:
         run: |+
           pnpm install -D svelte@4
           rm -rf node_modules
+      - name: Install ESLint ${{ matrix.eslint }}
+        run: |+
+          pnpm install -D eslint@${{ matrix.eslint }}
+          rm -rf node_modules
       - name: Install Packages
         run: pnpm install
       - name: Test
@@ -107,7 +115,7 @@ jobs:
           rm -rf node_modules
       - name: Install svelte@3
         run: |+
-          pnpm install -D svelte@3 @typescript-eslint/parser@5 @typescript-eslint/eslint-plugin@5
+          pnpm install -D svelte@3 @typescript-eslint/parser@5 @typescript-eslint/eslint-plugin@5 eslint@8
           rm -rf node_modules
       - name: Install Packages
         run: pnpm install

.eslintrc.js

@@ -74,7 +74,7 @@ Use `eslint.config.js` file to configure rules. See also: <https://eslint.org/do
 
 Example **eslint.config.js**:
 
-```mjs
+```js
 import eslintPluginSvelte from 'eslint-plugin-svelte';
 export default [
   // add more generic rule sets here, such as:

.github/workflows/NodeCI.yml

@@ -2,20 +2,9 @@ import esbuild from 'esbuild';
 import path from 'path';
 import fs from 'fs';
 import { fileURLToPath } from 'url';
-// const babelCore = require("@babel/core")
-// const t = require("@babel/types")
 
-const dirname = path.dirname(
-	fileURLToPath(
-		// @ts-expect-error -- Cannot change `module` option
-		import.meta.url
-	)
-);
+const dirname = path.dirname(fileURLToPath(import.meta.url));
 
-build(path.join(dirname, './src/eslint.mjs'), path.join(dirname, '../shim/eslint.mjs'), [
-	'assert',
-	'util'
-]);
 build(path.join(dirname, '../../node_modules/assert'), path.join(dirname, '../shim/assert.mjs'));
 
 /** build */

README.md

@@ -1,4 +1,3 @@
-/* eslint require-jsdoc:0 -- shim */
 function existsSync() {
 	return false;
 }

docs-svelte-kit/.eslintrc.cjs

@@ -1,4 +1,2 @@
-/* eslint require-jsdoc:0 -- shim */
-
 export {};
 export default {};

docs-svelte-kit/build-system/build.mts

@@ -1,4 +1,3 @@
-/* eslint require-jsdoc:0 -- shim */
 function _createRequire() {
 	return () => null;
 }

docs-svelte-kit/build-system/src/eslint.mjs

@@ -1,4 +1,3 @@
-/* eslint require-jsdoc:0 -- shim */
 function platform() {
 	return '';
 }