chore: run typechecking on js files

.eslint-doc-generatorrc.js

@@ -26,7 +26,11 @@ const config = {
   ],
   ruleListSplit: 'meta.docs.requiresTypeChecking',
   urlConfigs: `https://github.com/jest-community/eslint-plugin-jest/blob/main/README.md#shareable-configurations`,
-  postprocess: doc => format(doc, { ...prettierRC, parser: 'markdown' }),
+  postprocess: doc =>
+    format(doc, {
+      .../** @type {import('prettier').ResolveConfigOptions} */ (prettierRC),
+      parser: 'markdown',
+    }),
 };
 
 module.exports = config;

.eslintrc.js

@@ -2,7 +2,8 @@
 
 const globals = require('./src/globals.json');
 
-module.exports = {
+/** @type {import('eslint').Linter.LegacyConfig} */
+const config = {
   ignorePatterns: ['!.eslint-doc-generatorrc.js', '!.eslintrc.js'],
   parser: require.resolve('@typescript-eslint/parser'),
   extends: [
@@ -126,3 +127,5 @@ module.exports = {
     },
   ],
 };
+
+module.exports = config;

babel.config.js

@@ -3,14 +3,17 @@
 const semver = require('semver');
 const pkg = require('./package.json');
 
-const supportedNodeVersion = semver.minVersion(pkg.engines.node).version;
+const supportedNodeVersion = semver.minVersion(pkg.engines.node)?.version;
 
 // todo: https://github.com/babel/babel/issues/8529 :'(
-module.exports = {
+/** @type {import('@babel/core').TransformOptions} */
+const config = {
   plugins: ['replace-ts-export-assignment'],
   presets: [
     '@babel/preset-typescript',
     ['@babel/preset-env', { targets: { node: supportedNodeVersion } }],
   ],
   ignore: ['src/**/__tests__/fixtures/**'],
 };
+
+module.exports = config;

tsconfig.json

@@ -14,9 +14,17 @@
     "strict": true,
     "resolveJsonModule": true,
     "isolatedModules": true,
-    "skipLibCheck": false
+    "skipLibCheck": false,
+    "allowJs": true,
+    "checkJs": true
   },
-  "files": ["eslint-remote-tester.config.ts"],
+  "files": [
+    ".eslint-doc-generatorrc.js",
+    ".eslintrc.js",
+    "babel.config.js",
+    "eslint-remote-tester.config.ts",
+    "jest.config.ts"
+  ],
   "include": ["src/**/*"],
   "exclude": ["src/rules/__tests__/fixtures/**/*"]
 }