ESLint 9 Flat config example

eslint.config.ts

import type { Linter } from "eslint";

import { globalIgnores } from "eslint/config";
import { defineConfigWithVueTs, vueTsConfigs } from "@vue/eslint-config-typescript";
import pluginVue from "eslint-plugin-vue";
import pluginVitest from "@vitest/eslint-plugin";
import skipFormatting from "@vue/eslint-config-prettier/skip-formatting";

const commonRules = {
	"@typescript-eslint/no-explicit-any": "off",
	"@typescript-eslint/no-unused-expressions": "off",
	"no-unused-vars": "off",
	"@typescript-eslint/no-unused-vars": "warn",
	"@typescript-eslint/await-thenable": "error",
} satisfies Linter.RulesRecord;

export default defineConfigWithVueTs(
	{
		name: "files-to-lint",
		files: ["**/*.{js,ts,vue}"],
	},

	pluginVue.configs["flat/essential"],
	vueTsConfigs.recommended,

	{
		name: "js-rules",
		files: ["**/*.js"],
		rules: {},
	},

	{
		name: "ts-rules",
		files: ["**/*.ts"],
		rules: commonRules,
	},

	{
		name: "vue-rules",
		files: ["**/*.vue"],
		rules: commonRules,
	},

	{
		...pluginVitest.configs.recommended,
		files: ["src/**/__tests__/**"],
		rules: {
			"vitest/no-commented-out-tests": "warn",
			"@typescript-eslint/await-thenable": "error",
		},
	},

	globalIgnores(["**/dist/**", "**/coverage/**"]),

	skipFormatting
);