Oxlint + Svelte via Eslint (as of 2026-03)

.oxlintrc.json

{
	"$schema": "./node_modules/oxlint/configuration_schema.json",
	"plugins": ["typescript", "unicorn"],
	"categories": {
		"correctness": "error"
	},
	"ignorePatterns": ["**/*.svelte", "**/*.svelte.ts", "**/*.svelte.js"],
	"rules": {
		"no-case-declarations": "error",
		"no-empty": "error",
		"no-fallthrough": "error",
		"no-prototype-builtins": "error",
		"no-redeclare": "error",
		"no-regex-spaces": "error",
		"no-array-constructor": "error",
		"preserve-caught-error": "error",
		"@typescript-eslint/ban-ts-comment": "error",
		"@typescript-eslint/no-empty-object-type": "error",
		"@typescript-eslint/no-explicit-any": "error",
		"@typescript-eslint/no-namespace": "error",
		"@typescript-eslint/no-require-imports": "error",
		"@typescript-eslint/no-unnecessary-type-constraint": "error",
		"@typescript-eslint/no-unsafe-function-type": "error"
	},
	"overrides": [
		{
			"files": ["**/*.ts", "**/*.tsx", "**/*.mts", "**/*.cts"],
			"rules": {
				"no-var": "error",
				"prefer-const": "error",
				"prefer-rest-params": "error",
				"prefer-spread": "error"
			}
		}
	]
}

eslint.config.js

// For more info, see https://github.com/storybookjs/storybook/tree/next/code/lib/eslint-plugin#configuration-eslintrc
import storybook from 'eslint-plugin-storybook'

import depend from 'eslint-plugin-depend'
import e18e from '@e18e/eslint-plugin'
import prettier from 'eslint-config-prettier'
import { fileURLToPath } from 'node:url'
import { includeIgnoreFile } from '@eslint/compat'
import js from '@eslint/js'
import svelte from 'eslint-plugin-svelte'
import { defineConfig } from 'eslint/config'
import globals from 'globals'
import ts from 'typescript-eslint'
import svelteConfig from './svelte.config.js'
import oxlint from 'eslint-plugin-oxlint'

const gitignorePath = fileURLToPath(new URL('./.gitignore', import.meta.url))

const tsJsFiles = ['**/*.ts', '**/*.js', '**/*.mts', '**/*.cts']

export default defineConfig(
	includeIgnoreFile(gitignorePath),
	e18e.configs.recommended,
	js.configs.recommended,
	...ts.configs.recommended,
	...svelte.configs.recommended,
	...storybook.configs['flat/recommended'],
	prettier,
	...svelte.configs.prettier,
	{
		plugins: { depend },
		rules: depend.configs.recommended.rules
	},
	{
		languageOptions: { globals: { ...globals.browser, ...globals.node } },

		rules: {
			// typescript-eslint strongly recommend that you do not use the no-undef lint rule on TypeScript projects.
			// see: https://typescript-eslint.io/troubleshooting/faqs/eslint/#i-get-errors-from-the-no-undef-rule-about-global-variables-not-being-defined-even-though-there-are-no-typescript-errors
			'no-undef': 'off'
		}
	},
	{
		files: ['**/*.svelte', '**/*.svelte.ts', '**/*.svelte.js'],

		languageOptions: {
			parserOptions: {
				projectService: true,
				extraFileExtensions: ['.svelte'],
				parser: ts.parser,
				svelteConfig
			}
		}
	},
	// oxlint handles core JS/TS rules on .ts/.js — disable overlapping ESLint rules there
	// skips config[0] (ignorePatterns) so ESLint still lints .svelte/.svelte.ts files with all rules
	...oxlint
		.buildFromOxlintConfigFile('.oxlintrc.json')
		.slice(1)
		.map((config) => ({
			...config,
			files: config.files ?? tsJsFiles,
			ignores: [...(config.ignores ?? []), '**/*.svelte.ts', '**/*.svelte.js']
		}))
)