eslint.config.mjs

import tseslint from "typescript-eslint";
import eslintJs from "@eslint/js";
import importPlugin from "eslint-plugin-import";
import unicornPlugin from "eslint-plugin-unicorn";
import globals from "globals";

export default tseslint.config(
	eslintJs.configs.recommended,
	importPlugin.flatConfigs.errors,
	unicornPlugin.configs["flat/recommended"],
	tseslint.configs.strictTypeChecked,
	{
		ignores: [".db/", ".yarn/", "coverage/", "build/", "**/*.js", "**/*.test.js", "**/*.d.ts", "**/*.mjs"]
	},
	{
		languageOptions: {
			parserOptions: {
				project: true,
				projectService: true,
				tsconfigRootDir: import.meta.dirname
			},
			globals: {
				...globals.browser,
				...globals.es2025,
				...globals.node,
				core: "readonly",
				sb: "readonly"
			},
			ecmaVersion: 2025,
			sourceType: "module"
		},
		rules: {
			"array-bracket-newline": ["warn", "consistent"],
			"array-bracket-spacing": ["warn", "never"],
			"array-element-newline": ["warn", "consistent"],
			"arrow-body-style": ["warn", "as-needed"],
			"arrow-spacing": ["warn", {
				after: true,
				before: true
			}],
			"brace-style": ["warn", "stroustrup", {
				allowSingleLine: true
			}],
			"comma-dangle": ["warn", "never"],
			curly: ["warn", "all"],
			"dot-location": ["warn", "property"],
			"dot-notation": "warn",
			"eol-last": ["warn", "always"],
			eqeqeq: "error",
			"function-call-argument-newline": ["warn", "consistent"],
			"import/extensions": ["error", "always"],
			"import/no-unresolved": "off",
			"implicit-arrow-linebreak": ["error", "beside"],
			indent: ["warn", "tab", {
				SwitchCase: 1
			}],
			"key-spacing": ["warn", {
				afterColon: true,
				beforeColon: false,
				mode: "strict"
			}],
			"keyword-spacing": ["warn", {
				after: true,
				before: true
			}],
			"lines-between-class-members": ["warn", "always", {
				exceptAfterSingleLine: true
			}],
			"max-nested-callbacks": ["warn", {
				max: 2
			}],
			"max-params": ["warn", {
				max: 5
			}],
			"max-statements-per-line": ["error", {
				max: 1
			}],
			"multiline-ternary": ["warn", "always-multiline"],
			"new-cap": ["warn", {
				capIsNew: false,
				newIsCap: true,
				properties: false
			}],
			"new-parens": ["error", "always"],
			"newline-per-chained-call": ["warn", {
				ignoreChainWithDepth: 3
			}],
			"no-bitwise": "error",
			"no-console": "off",
			"no-control-regex": "off",
			"no-duplicate-imports": "error",
			"no-empty-pattern": "error",
			"no-lonely-if": "warn",
			"no-mixed-operators": ["error", {
				groups: [
					["&&", "||"],
					["&", "|", "^", "~", "<<", ">>", ">>>"],
					["==", "!=", "===", "!==", ">", ">=", "<", "<="]
				]
			}],
			"no-multi-assign": "error",
			"no-multi-spaces": "warn",
			"no-multi-str": "warn",
			"no-multiple-empty-lines": ["warn", {
				max: 2,
				maxBOF: 0,
				maxEOF: 0
			}],
			"no-nested-ternary": "off",
			"no-new": "warn",
			"no-new-object": "error",
			"no-new-wrappers": "error",
			"no-proto": "error",
			"no-return-assign": "error",
			"no-return-await": "off",
			"no-self-compare": "warn",
			"no-sequences": "error",
			"no-trailing-spaces": ["warn", {
				skipBlankLines: true
			}],
			"no-underscore-dangle": "off",
			"no-unneeded-ternary": "warn",
			"no-unused-vars": "off",
			"no-useless-computed-key": "warn",
			"no-useless-constructor": "warn",
			"no-useless-rename": "error",
			"no-var": "error",
			"no-whitespace-before-property": "warn",
			"no-unused-private-class-members": "warn",
			// "no-use-before-define": "error",
			"no-with": "error",
			"object-curly-newline": ["warn", {
				consistent: true
			}],
			"object-curly-spacing": ["warn", "always", {
				arraysInObjects: false,
				objectsInObjects: true
			}],
			"object-property-newline": ["warn", {
				allowAllPropertiesOnSameLine: true
			}],
			"object-shorthand": ["warn", "properties"],
			"one-var": ["warn", "never"],
			"operator-linebreak": ["warn", "before"],
			"padded-blocks": ["warn", "never"],
			"prefer-arrow-callback": "warn",
			"prefer-const": ["warn", {
				destructuring: "all"
			}],
			"prefer-exponentiation-operator": "warn",
			"prefer-numeric-literals": "warn",
			"prefer-object-spread": "warn",
			"prefer-rest-params": "error",
			"prefer-template": "warn",
			"quote-props": ["warn", "as-needed"],
			quotes: ["warn", "double", {
				allowTemplateLiterals: true
			}],
			"rest-spread-spacing": ["warn", "never"],
			semi: ["warn", "always"],
			"semi-spacing": ["warn", {
				before: false,
				after: true
			}],
			"semi-style": ["warn", "last"],
			"sort-keys": ["off", "asc"],
			"space-before-blocks": ["warn", "always"],
			"space-before-function-paren": ["warn", "always"],
			"space-in-parens": ["warn", "never"],
			"space-infix-ops": "error",
			"space-unary-ops": "warn",
			"spaced-comment": ["warn", "always"],
			"switch-colon-spacing": ["warn", {
				after: true,
				before: false
			}],
			"symbol-description": "off",
			"template-curly-spacing": ["warn", "never"],
			"template-tag-spacing": ["warn", "always"],
			"unicorn/catch-error-name": ["warn", {
				name: "e"
			}],
			"unicorn/prefer-spread": "off",
			"unicorn/empty-brace-spaces": "warn",
			"unicorn/new-for-builtins": "error",
			"unicorn/no-array-for-each": "error",
			"unicorn/no-array-push-push": "warn",
			"unicorn/no-console-spaces": "warn",
			"unicorn/no-lonely-if": "warn",
			"unicorn/no-instanceof-array": "error",
			"unicorn/no-nested-ternary": "warn",
			"unicorn/no-new-buffer": "error",
			"unicorn/no-unreadable-array-destructuring": "error",
			"unicorn/no-unsafe-regex": "off",
			"unicorn/number-literal-case": "warn",
			"unicorn/numeric-separators-style": ["warn", {
				onlyIfContainsSeparator: true
			}],
			"unicorn/prefer-array-find": "warn",
			"unicorn/prefer-array-flat": "warn",
			"unicorn/prefer-array-flat-map": "warn",
			"unicorn/prefer-array-index-of": "warn",
			"unicorn/prefer-array-some": "warn",
			"unicorn/prefer-regexp-test": "warn",
			"unicorn/prefer-date-now": "warn",
			"unicorn/prefer-includes": "warn",
			"unicorn/prefer-math-trunc": "warn",
			"unicorn/prefer-string-starts-ends-with": "warn",
			"unicorn/prefer-string-trim-start-end": "warn",
			"unicorn/throw-new-error": "error",

			"@typescript-eslint/restrict-template-expressions": ["warn", { // Allow numbers in template expressions without requiring explicit stringification
				allowNumber: true
			}],
			"@typescript-eslint/no-confusing-void-expression": ["warn", { // Ignore arrow functions implicitly "returning" another void function's result
				ignoreVoidReturningFunctions: true
			}],
			"@typescript-eslint/no-unused-vars": "warn", // Only warn for unused vars instead of resulting in an error
			"@typescript-eslint/no-unnecessary-condition": "warn", // Only warn for unnecessary conditions  instead of resulting in an error

			"unicorn/prevent-abbreviations": "off",
			"unicorn/no-null": "off",
			"unicorn/explicit-length-check": "off",
			"unicorn/no-negated-condition": "off",
			"unicorn/prefer-ternary": "off",
			"unicorn/no-for-loop": "off",
			"unicorn/text-encoding-identifier-case": "off", // Also applies to standalone strings rather than arguments => disable
			"unicorn/no-typeof-undefined": "off",
			"unicorn/no-static-only-class": "off",
			"unicorn/switch-case-braces": "off",
			"unicorn/prefer-default-parameters": "off",
			"unicorn/prefer-type-error": "off",
			"unicorn/no-anonymous-default-export": "off", // Remove when refactored to imports/exports
			"unicorn/prefer-module": "off", // Remove when refactored to imports/exports too
			"unicorn/no-array-method-this-argument": "off", // Doesn't work for custom array methods
			"unicorn/no-array-callback-reference": "off", // Doesn't work for custom array methods either
			"unicorn/prefer-event-target": "off", // Not necessary at the moment, can be considered if project moves away from Node
			"unicorn/prefer-switch": ["error", {
				minimumCases: 4
			}],

			"wrap-iife": ["warn", "inside"],
			yoda: "error"
		}
	}
);