@typescript-eslint/utils

What is @typescript-eslint/utils?

The @typescript-eslint/utils package provides utility functions and types that are used across the TypeScript ESLint project. It's designed to help with the development of ESLint rules, parsers, and plugins by providing a consistent set of tools for working with TypeScript code. This package is particularly useful for those creating custom ESLint rules or integrating TypeScript more deeply into their ESLint configurations.

What are @typescript-eslint/utils's main functionalities?

AST Utilities

AST Utilities provide functions to work with Abstract Syntax Tree (AST) nodes. These utilities can help in identifying node types, such as checking if a node is an identifier or a literal, which is useful when writing custom ESLint rules.

import { ASTUtils } from '@typescript-eslint/utils';
const { isIdentifier, isLiteral } = ASTUtils;

Type Checking

This feature allows rule developers to access TypeScript's type checker, enabling them to perform more sophisticated analyses, such as type inference or type checking, within their custom ESLint rules.

import { ESLintUtils } from '@typescript-eslint/utils';
const { getParserServices } = ESLintUtils;
const parserServices = getParserServices(context);
const checker = parserServices.program.getTypeChecker();

ESLint Rule Creation

Provides a utility for creating ESLint rules with a consistent structure and metadata. This is particularly useful for developers creating custom rules for projects that use TypeScript.

import { ESLintUtils } from '@typescript-eslint/utils';
const createRule = ESLintUtils.RuleCreator(name => `https://example.com/rule/${name}`);
const myRule = createRule({
  name: 'my-custom-rule',
  meta: { /* rule metadata */ },
  defaultOptions: [],
  create(context) { /* rule implementation */ }
});

Other packages similar to @typescript-eslint/utils

eslint-plugin-import

This package provides a set of ESLint rules that help ensure proper import/export syntax and order. While it focuses on module syntax, it doesn't offer TypeScript-specific utilities or type checking capabilities like @typescript-eslint/utils.

eslint-utils

Similar to @typescript-eslint/utils, eslint-utils provides utility functions for working with ESLint and AST nodes. However, it is not specifically tailored for TypeScript, lacking direct integrations with TypeScript's type system and parser.

README

Utils for ESLint Plugins

Utilities for working with TypeScript + ESLint together.

Exports

Name	Description
ASTUtils	Tools for operating on the ESTree AST. Also includes the eslint-utils package, correctly typed to work with the types found in TSESTree
ESLintUtils	Tools for creating ESLint rules with TypeScript.
JSONSchema	Types from the @types/json-schema package, re-exported to save you having to manually import them. Also ensures you're using the same version of the types as this package.
TSESLint	Types for ESLint, correctly typed to work with the types found in TSESTree.
TSESLintScope	The eslint-scope package, correctly typed to work with the types found in both TSESTree and TSESLint
TSESTree	Types for the TypeScript flavor of ESTree created by @typescript-eslint/typescript-estree.
AST_NODE_TYPES	An enum with the names of every single node found in TSESTree.
AST_TOKEN_TYPES	An enum with the names of every single token found in TSESTree.
ParserServices	Typing for the parser services provided when parsing a file using @typescript-eslint/typescript-estree.

Contributing

See the contributing guide here

Changelog

5.26.0 (2022-05-23)

Bug Fixes

• ast-spec: add SpreadElement to ArrayExpression.elements (#5025) (9f3121b)
• eslint-plugin: [member-delimiter-style] autofixer result is not as expected when comments after the delimiter with option delimiter: 'none' (#5029) (ed7b5f6)
• eslint-plugin: [member-delimiter-style] autofixer result is not as expected with option delimiter: 'none' (#5023) (9e97a11)
• eslint-plugin: [prefer-readonly] correct issue with anonymus functions (#4974) (952e2f0), closes #2590

Features

• [4.7] support instantiation expressions (#4938) (79fbc77)
• [4.7] support optional variance annotation (#4831) (7e7b24c)
• typescript-estree: extends constraints for infer (#4830) (8cbbcc3)