ESLint

eslint.config.js

/*
	bun add -D @eslint/compat @eslint/js eslint-plugin-svelte eslint globals typescript-eslint @stylistic/eslint-plugin eslint-plugin-unused-imports eslint-plugin-import-no-duplicates-prefix-resolved-path eslint-plugin-import-x eslint-import-resolver-typescript @sveltejs/vite-plugin-svelte eslint-module-utils
*/

import { includeIgnoreFile } from '@eslint/compat'
import js from '@eslint/js'
import svelte from 'eslint-plugin-svelte'
import { globalIgnores } from 'eslint/config'
import globals from 'globals'
import { fileURLToPath } from 'node:url'
import ts from 'typescript-eslint'
import svelteConfig from './sveltekit-app/svelte.config.js'
import stylistic from '@stylistic/eslint-plugin'
import unusedImports from 'eslint-plugin-unused-imports'
// @ts-expect-error Is not typed but works fine! Replaces import-x/no-duplicates issue
import importPrefix from 'eslint-plugin-import-no-duplicates-prefix-resolved-path'
import importX from 'eslint-plugin-import-x'
import 'eslint-import-resolver-typescript' // required for eslint-plugin-import-x

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

// Improved ignore patterns to exclude problematic files and directories
const ignorePatterns = [
	'**/eslint.config.js',
	'**/svelte.config.js',
	'**/.svelte-kit/*',
	'**/node_modules/**',
	'**/node_modules/zod/**',
	'**/node_modules/zod/lib/**',
	'**/node_modules/zod/lib/index.mjs',
	'**/.wrangler/*',
	'**/.git/*',
	'**/.mongodb/*',
	'**/.cloudflare/*',
	'**/lang/src/paraglide/*',
	'**/src-tauri/target/*',
	'**/dist/**',
	'**/build/**',
	'**/.turbo/**'
]

export default ts.config(
	globalIgnores(ignorePatterns),
	includeIgnoreFile(gitignorePath),
	js.configs.recommended,
	...ts.configs.recommended,
	...svelte.configs.recommended,
	{
		files: ['**/*.{js,mjs,cjs,ts,svelte}'],
		extends: [importX.flatConfigs.recommended, importX.flatConfigs.typescript],
		ignores: ['**/node_modules/**'],
		languageOptions: {
			globals: {
				...globals.browser,
				...globals.node 
			},
			parserOptions: {
				projectService: true,
				extraFileExtensions: ['.svelte'],
				parser: ts.parser,
				svelteConfig,
				// Optimizing for performance
				cacheLifetime: {
					glob: 'Infinity'
				},
				// Add cache strategy for better performance
				tsconfigRootDir: '.',
				project: ['./tsconfig.json', './*/tsconfig.json', './apps/*/tsconfig.json'],
				cache: true
			}
		},
		plugins: {
			'@stylistic': stylistic,
			'unused-imports': unusedImports,
			'import-no-duplicates-prefix-resolved-path': importPrefix
		},
		rules: {
			// Disabling rules that might slow down the linting process
			'no-undef': 'off',
			'no-empty-pattern': 'off',
			'@typescript-eslint/no-unsafe-assignment': 'off',
			'@typescript-eslint/no-unsafe-member-access': 'off',
			'@typescript-eslint/no-unsafe-call': 'off',
			'@typescript-eslint/no-unsafe-return': 'off',
			'no-inner-declarations': 'off', // 700 ms
			'svelte/require-store-reactive-access': 'off', // 1000 ms
			'import-x/namespace': 'off', // 2000 ms
			'import-x/no-unresolved': 'off', // 80 ms

			'import-x/no-duplicates': 'off', // doesn't work with module declarations
			'import-no-duplicates-prefix-resolved-path/no-duplicates': [
				'warn',
				{
					'prefixResolvedPathWithImportName': true,
					'prefer-inline': true,
				},
			],

			'unused-imports/no-unused-imports': 'warn',
			'unused-imports/no-unused-vars': [
				'warn',
				{
					'vars': 'all',
					'varsIgnorePattern': '^_',
					'args': 'after-used',
					'argsIgnorePattern': '^_',
				},
			],

			// TypeScript Rules
			'@typescript-eslint/no-unused-vars': 'off',
			'@typescript-eslint/no-empty-interface': 'off',
			'@typescript-eslint/no-empty-object-type': 'off',
			'@stylistic/member-delimiter-style': ['error',
				{
					'multiline': {
						'delimiter': 'none',
						'requireLast': false
					},
					'singleline': {
						'delimiter': 'comma',
						'requireLast': false
					}
				}],
			'@stylistic/type-annotation-spacing': ['error',
				{
					'before': false,
					'after': true,
					'overrides': {
						'arrow': {
							'before': true,
							'after': true
						}
					}
				}],
			'@stylistic/type-generic-spacing': 'error',
			'@typescript-eslint/naming-convention': [
				'error',
				{
					'selector': 'interface',
					'format': ['PascalCase'],
					'custom': {
						'regex': '^I[A-Z]',
						'match': false
					}
				}
			],

			// @stylistic - https://eslint.style/packages/default
			'@stylistic/quotes': ['error',
				'single',
				{ allowTemplateLiterals: 'always' }],
			'@stylistic/semi': ['error', 'never'],
			'@stylistic/comma-dangle': ['error', 'never'],
			'@stylistic/object-curly-spacing': ['error', 'always'],
			'@stylistic/space-before-function-paren': ['error',
				{
					'anonymous': 'never',
					'named': 'never',
					'asyncArrow': 'always'
				}],
			'@stylistic/space-before-blocks': ['error', 'always'],
			'@stylistic/indent': [
				'error',
				'tab',
				{ 'ignoredNodes': ['ConditionalExpression'] }
			],
			'@stylistic/indent-binary-ops': ['error', 'tab'],
			'@stylistic/array-bracket-newline': ['error', 'consistent'],
			'@stylistic/array-element-newline': ['error',
				{
					multiline: true,
					minItems: 3 
				}],
			'@stylistic/space-infix-ops': ['error'],
			'@stylistic/comma-spacing': ['error',
				{
					'before': false,
					'after': true 
				}],
			'@stylistic/function-call-argument-newline': ['error', 'consistent'],
			'@stylistic/function-paren-newline': ['error', 'multiline'],
			'@stylistic/key-spacing': ['error',
				{
					'beforeColon': false,
					'afterColon': true,
					'mode': 'strict'
				}],
			'@stylistic/block-spacing': ['error', 'always'],
			'@stylistic/no-multi-spaces': ['error', { 'ignoreEOLComments': true }],
			'@stylistic/object-curly-newline': [
				'error',
				{ multiline: true }
			],
			'@stylistic/object-property-newline': ['error', { allowAllPropertiesOnSameLine: false }],

			// Svelte Rules
			'svelte/html-quotes': ['error', { 'prefer': 'single' }],
			'svelte/max-attributes-per-line': [
				'error',
				{
					'multiline': 1,
					'singleline': 2
				}
			],
			'svelte/indent': ['error', { 'indent': 'tab' }],
			'svelte/shorthand-attribute': 'error',
			'svelte/shorthand-directive': 'error',
			'svelte/sort-attributes': 'error',
			'svelte/spaced-html-comment': 'error',
			'svelte/no-spaces-around-equal-signs-in-attribute': 'error',
			'svelte/first-attribute-linebreak': [
				'error',
				{
					'multiline': 'below',
					'singleline': 'beside'
				}
			],
			'svelte/html-closing-bracket-new-line': [
				'error',
				{
					'singleline': 'never',
					'multiline': 'always',
					'selfClosingTag': {
						'singleline': 'never',
						'multiline': 'always'
					}
				}
			],
			'svelte/html-closing-bracket-spacing': [
				'error',
				{
					'startTag': 'never',
					'endTag': 'never',
					'selfClosingTag': 'always'
				}
			]
		}
	}
)

svelte.config.js

import { vitePreprocess } from '@sveltejs/vite-plugin-svelte'

/** @type {import('@sveltejs/kit').Config} */
const config = {
	preprocess: [ vitePreprocess() ],
	compilerOptions: { runes: true },
	kit: {}
}

export default config

tsconfig.base.json

{
	"compilerOptions": {
		"lib": ["ESNext", "DOM", "DOM.Iterable", "DOM.AsyncIterable"],
		"allowJs": true,
		"checkJs": true,
		"esModuleInterop": true,
		"forceConsistentCasingInFileNames": true,
		"resolveJsonModule": true,
		"skipLibCheck": true,
		"sourceMap": true,
		"strict": true,
		"moduleResolution": "bundler",
		"module": "ESNext",
		"target": "ESNext",
		"verbatimModuleSyntax": true,
		"isolatedModules": true,
		"noImplicitAny": false,
	},
	"include": [
		"**/*"
	],
	"exclude": [
		"./**/*.config.js",
		"./**/*.config.ts",
		"./**/*.config.cjs",
		"./node_modules"
	]
}