feat: export ESLint.defaultConfig (#18983)

* feat: export `ESLint.defaultConfig`

* fix: freeze defaultConfig object

* fix: update defaultConfig type

* refactor: freeze default config while exporting

* docs: udpate description

Author: snitin315

docs/src/integrate/nodejs-api.md

@@ -330,6 +330,16 @@ The version string of ESLint. E.g. `"7.0.0"`.
 
 This is a static property.
 
+### ◆ ESLint.defaultConfig
+
+```js
+const defaultConfig = ESLint.defaultConfig;
+```
+
+The default configuration that ESLint uses internally. This is provided for tooling that wants to calculate configurations using the same defaults as ESLint. Keep in mind that the default configuration may change from version to version, so you shouldn't rely on any particular keys or values to be present.
+
+This is a static property.
+
 ### ◆ ESLint.outputFixes(results)
 
 ```js

lib/config/default-config.js

@@ -15,7 +15,7 @@ const Rules = require("../rules");
 // Helpers
 //-----------------------------------------------------------------------------
 
-exports.defaultConfig = [
+exports.defaultConfig = Object.freeze([
     {
         plugins: {
             "@": {
@@ -72,4 +72,4 @@ exports.defaultConfig = [
             ecmaVersion: "latest"
         }
     }
-];
+]);

lib/eslint/eslint.js

@@ -15,6 +15,7 @@ const path = require("node:path");
 const { version } = require("../../package.json");
 const { Linter } = require("../linter");
 const { getRuleFromConfig } = require("../config/flat-config-helpers");
+const { defaultConfig } = require("../config/default-config");
 const {
     Legacy: {
         ConfigOps: {
@@ -52,6 +53,7 @@ const { ConfigLoader, LegacyConfigLoader } = require("../config/config-loader");
 //------------------------------------------------------------------------------
 
 // For VSCode IntelliSense
+/** @typedef {import("../cli-engine/cli-engine").ConfigArray} ConfigArray */
 /** @typedef {import("../shared/types").ConfigData} ConfigData */
 /** @typedef {import("../shared/types").DeprecatedRuleInfo} DeprecatedRuleInfo */
 /** @typedef {import("../shared/types").LintMessage} LintMessage */
@@ -522,6 +524,15 @@ class ESLint {
         return version;
     }
 
+    /**
+     * The default configuration that ESLint uses internally. This is provided for tooling that wants to calculate configurations using the same defaults as ESLint.
+     * Keep in mind that the default configuration may change from version to version, so you shouldn't rely on any particular keys or values to be present.
+     * @type {ConfigArray}
+     */
+    static get defaultConfig() {
+        return defaultConfig;
+    }
+
     /**
      * Outputs fixes from the given results to files.
      * @param {LintResult[]} results The lint results.

lib/types/index.d.ts

@@ -1396,6 +1396,12 @@ export class ESLint {
 
     static readonly version: string;
 
+    /**
+     * The default configuration that ESLint uses internally. This is provided for tooling that wants to calculate configurations using the same defaults as ESLint.
+     * Keep in mind that the default configuration may change from version to version, so you shouldn't rely on any particular keys or values to be present.
+     */
+    static readonly defaultConfig: Linter.Config[];
+
     static outputFixes(results: ESLint.LintResult[]): Promise<void>;
 
     static getErrorResults(results: ESLint.LintResult[]): ESLint.LintResult[];

tests/lib/eslint/eslint.js

@@ -29,6 +29,7 @@ const shell = require("shelljs");
 const hash = require("../../../lib/cli-engine/hash");
 const { unIndent, createCustomTeardown } = require("../../_utils");
 const { shouldUseFlatConfig } = require("../../../lib/eslint/eslint");
+const { defaultConfig } = require("../../../lib/config/default-config");
 const coreRules = require("../../../lib/rules");
 const espree = require("espree");
 
@@ -158,6 +159,10 @@ describe("ESLint", () => {
                 assert.strictEqual(ESLint.configType, "flat");
             });
 
+            it("should have the defaultConfig static property", () => {
+                assert.deepStrictEqual(ESLint.defaultConfig, defaultConfig);
+            });
+
             it("the default value of 'options.cwd' should be the current working directory.", async () => {
                 process.chdir(__dirname);
                 try {