Update for ESLint 10

Author: fasttime

.github/workflows/nodejs.yml

@@ -16,8 +16,8 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-    - uses: actions/checkout@v5
-    - uses: actions/setup-node@v5
+    - uses: actions/checkout@v6
+    - uses: actions/setup-node@v6
       with:
         node-version: 24
     - run: |
@@ -36,15 +36,35 @@ jobs:
         node-version: ['12', '14', '16']
 
     steps:
-    - uses: actions/checkout@v5
-    - uses: actions/setup-node@v5
+    - uses: actions/checkout@v6
+    - uses: actions/setup-node@v6
       with:
         node-version: ${{ matrix.node-version }}
     - run: |
         npm ci
         npm install eslint@8
         npm test
 
+  test-eslint-8-and-9-only:
+
+    name: test (Node.js ${{ matrix.node-version }})
+
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node-version: ['18']
+
+    steps:
+    - uses: actions/checkout@v6
+    - uses: actions/setup-node@v6
+      with:
+        node-version: ${{ matrix.node-version }}
+    - run: |
+        npm ci
+        npm install eslint@9
+        npm test
+
   test:
 
     name: test (Node.js ${{ matrix.node-version }})
@@ -53,13 +73,14 @@ jobs:
 
     strategy:
       matrix:
-        node-version: ['18', '20', '22', '24']
+        node-version: ['20', '22', '24']
 
     steps:
-    - uses: actions/checkout@v5
-    - uses: actions/setup-node@v5
+    - uses: actions/checkout@v6
+    - uses: actions/setup-node@v6
       with:
         node-version: ${{ matrix.node-version }}
     - run: |
         npm ci
+        npm install eslint@10
         npm test

README.md

@@ -1,11 +1,11 @@
 # gulp-eslint-new · [![npm version][npm badge]][npm URL]
 
-> A [gulp](https://gulpjs.com/) plugin to lint code with [ESLint](https://eslint.org/) 8 and 9.
+> A [gulp](https://gulpjs.com/) plugin to lint code with [ESLint](https://eslint.org/) 8, 9, and 10.
 
 ## Installation
 
 Make sure that you are using a version of Node.js supported by your version of ESLint.
-See prerequisites for [ESLint 8](https://eslint.org/docs/v8.x/use/getting-started#prerequisites) and [ESLint 9](https://eslint.org/docs/v9.x/use/getting-started#prerequisites).
+See prerequisites for [ESLint 8](https://eslint.org/docs/v8.x/use/getting-started#prerequisites), [ESLint 9](https://eslint.org/docs/v9.x/use/getting-started#prerequisites), or [ESLint 10](https://eslint.org/docs/v10.x/use/getting-started#prerequisites).
 For TypeScript support, you need TypeScript 4.8 or later.
 
 To install gulp-eslint-new, [use](https://docs.npmjs.com/cli/install) [npm](https://docs.npmjs.com/about-npm):
@@ -14,24 +14,25 @@ To install gulp-eslint-new, [use](https://docs.npmjs.com/cli/install) [npm](http
 npm i -D gulp-eslint-new
 ```
 
-gulp-eslint-new will also install the latest version of ESLint 9, unless another one is found.
+gulp-eslint-new will also install the latest version of ESLint 10, unless another one is found.
 To use a particular version of ESLint, install it by yourself.
-For example, to use ESLint 8.8.0:
+For example, to use ESLint 8.57.1:
 
 ```console
-npm i -D gulp-eslint-new eslint@8.8.0
+npm i -D gulp-eslint-new eslint@8.57.1
 ```
 
 ## Migrating
 
 If you are migrating from [gulp-eslint][gulp-eslint], you probably won't need to make any substantial changes to your gulp task, as the API is widely compatible.
 Note though that many options have changed: the current options are documented in the [`gulpESLintNew(options)`](#gulpeslintnewoptions) section.
 
-Also note that gulp-eslint-new is designed to work with ESLint 8 or 9, whereas the latest release of gulp-eslint only supports ESLint 6: you will need to update your project to address breaking changes in ESLint.
+Also note that gulp-eslint-new is designed to work with ESLint 8, 9 or 10, whereas the latest release of gulp-eslint only supports ESLint 6: you will need to update your project to address breaking changes in ESLint.
 You can follow the links below for more information.
 * [Breaking changes for users from ESLint 6 to ESLint 7](https://eslint.org/docs/user-guide/migrating-to-7.0.0#breaking-changes-for-users)
 * [Breaking changes for users from ESLint 7 to ESLint 8](https://eslint.org/docs/user-guide/migrate-to-8.0.0#breaking-changes-for-users)
 * [Breaking changes for users from ESLint 8 to ESLint 9](https://eslint.org/docs/user-guide/migrate-to-9.0.0#breaking-changes-for-users)
+* [Breaking changes for users from ESLint 9 to ESLint 10](https://eslint.org/docs/user-guide/migrate-to-10.0.0#breaking-changes-for-users)
 
 
 ## Usage
@@ -149,15 +150,13 @@ See the linked content for details about each option.
 
 Type: `"eslintrc" | "flat" | null`
 
-ESLint supports two types of configuration: a [new config](https://eslint.org/docs/user-guide/configure/configuration-files) type, aka flat config, based on file `eslint.config.*`, and a [legacy config](https://eslint.org/docs/user-guide/configure/configuration-files-deprecated) type, or eslintrc config, based on file `.eslintrc`.
+ESLint supports two configuration formats: a [new config](https://eslint.org/docs/user-guide/configure/configuration-files) type, aka flat config, based on file `eslint.config.*`, and a [legacy config](https://eslint.org/docs/user-guide/configure/configuration-files-deprecated) type, or eslintrc config, based on file `.eslintrc`.
 
-In ESLint 8, the default config type is the legacy config, and the new config is partly supported depending on the version of ESLint used.
-To use the the new config with ESLint 8 in gulp-eslint-new, set the option `configType` to `"flat"`.
+* **ESLint 8**: Uses the legacy config by default. Flat config is partially supported depending on the version. In gulp-eslint-new, set `configType: "flat"` to enable flat config.
+* **ESLint 9**: Uses flat config by default. To use legacy config in gulp-eslint-new, set `configType: "eslintrc"`.  
+* **ESLint 10**: Only supports flat config. Setting `configType: "eslintrc"` in gulp-eslint-new will result in an error.
 
-ESLint 9 uses the new config type by default.
-To use the legacy config with ESLint 9 in gulp-eslint-new, set the option `configType` to `"eslintrc"`.
-
-The new and legacy config types differ significantly in the available options and their usage.
+The new and legacy config formats differ significantly in the available options and their usage.
 Refer to the respective documentation in ESLint for the specifics of each options.
 
 ##### `options.cwd`

eslint.config.js

@@ -12,6 +12,7 @@ createConfig
         files:              ['**/*.js'],
         jsVersion:          2020,
         languageOptions:    { sourceType: 'script' },
+        rules:              { 'object-shorthand': ['error', 'always', { avoidQuotes: true }] },
     },
     {
         files:              ['test/*.spec.js'],

lib/eslint.d.ts

@@ -1,6 +1,40 @@
 import type { ESLint, Linter } from 'eslint';
 
-type ESLintrcOptions    = ESLint.LegacyOptions;
+interface ESLintrcOptions
+{
+    // File enumeration
+    cwd?:                           string | undefined;
+    errorOnUnmatchedPattern?:       boolean | undefined;
+    extensions?:                    string[] | undefined;
+    globInputPaths?:                boolean | undefined;
+    ignore?:                        boolean | undefined;
+    ignorePath?:                    string | undefined;
+
+    // Linting
+    allowInlineConfig?:             boolean | undefined;
+    baseConfig?:                    Linter.LegacyConfig | undefined;
+    overrideConfig?:                Linter.LegacyConfig | undefined;
+    overrideConfigFile?:            string | undefined;
+    plugins?:                       Record<string, ESLint.Plugin> | undefined;
+    reportUnusedDisableDirectives?: Linter.StringSeverity | undefined;
+    resolvePluginsRelativeTo?:      string | undefined;
+    rulePaths?:                     string[] | undefined;
+    useEslintrc?:                   boolean | undefined;
+
+    // Autofix
+    fix?:
+    boolean | ((message: Linter.LintMessage) => boolean) | undefined;
+    fixTypes?:                      FixType[] | null | undefined;
+
+    // Caching
+    cache?:                         boolean | undefined;
+    cacheLocation?:                 string | undefined;
+    cacheStrategy?:                 ESLint.CacheStrategy | undefined;
+
+    // Unused
+    flags?:                         string[] | undefined;
+}
+
 type FlatESLintOptions  = ESLint.Options;
 type FormatterFunction  = ESLint.FormatterFunction;
 type LintMessage        = Linter.LintMessage;

lib/util.js

@@ -259,6 +259,8 @@ exports.hasOwn = hasOwn;
 
 exports.isErrorMessage = isErrorMessage;
 
+exports.isEslintrcESLintConstructor = isEslintrcESLintConstructor;
+
 exports.isWarningMessage = isWarningMessage;
 
 const makeNPMLink =
@@ -286,21 +288,35 @@ const FORBIDDEN_OPTIONS =
 
 const requireESLint = eslintPkg => require(eslintPkg).ESLint;
 
+function requireEslintrcESLint(eslintPkg)
+{
+    const { LegacyESLint } = require(`${eslintPkg}/use-at-your-own-risk`);
+    if (LegacyESLint) return LegacyESLint;
+
+    const { satisfies } = require('semver');
+    const { ESLint } = require(eslintPkg);
+    if (satisfies(ESLint.version, '8')) return ESLint;
+
+    const message =
+    'The version of ESLint you are using does not support eslintrc config. ' +
+    'Eslintrc config is not available in ESLint 10.';
+    throw Error(message);
+}
+
 function requireFlatESLint(eslintPkg)
 {
     const { FlatESLint } = require(`${eslintPkg}/use-at-your-own-risk`);
-    if (FlatESLint == null)
-    {
-        const message =
-        'The version of ESLint you are using does not support flat config. ' +
-        'To use flat config, upgrade to ESLint 8.21 or later.';
-        throw Error(message);
-    }
-    return FlatESLint;
-}
+    if (FlatESLint) return FlatESLint;
 
-const requireEslintrcESLint =
-eslintPkg => require(`${eslintPkg}/use-at-your-own-risk`).LegacyESLint || require(eslintPkg).ESLint;
+    const { satisfies } = require('semver');
+    const { ESLint } = require(eslintPkg);
+    if (!satisfies(ESLint.version, '8')) return ESLint;
+
+    const message =
+    'The version of ESLint you are using does not support flat config. ' +
+    'Flat config is available in ESLint 8.21 or later.';
+    throw Error(message);
+}
 
 /**
  * Throws an error about invalid options passed to gulp-eslint-new.
@@ -402,15 +418,23 @@ async ({ cwd, eslint }, formatter) =>
     if (formatter === undefined)
     {
         const { format } = await eslint.loadFormatter();
-        return {
-            format: results =>
-            format(results)
-            .replace
-            (
-                / with the `--fix` option\.(?=(\u001b\[\d+m|\n)+$)/,
-                ` - see ${makeNPMLink('autofix')}`,
-            ),
+        const formatterObj =
+        {
+            format:
+            results =>
+            {
+                const stylishText = format(results);
+                const text =
+                stylishText
+                .replace
+                (
+                    / with the `--fix` option\.(?=(\u001b\[\d+m|\n)+$)/,
+                    ` - see ${makeNPMLink('autofix')}`,
+                );
+                return text;
+            },
         };
+        return formatterObj;
     }
     if (isObject(formatter) && typeof formatter.format === 'function')
         return formatter;