@typescript-eslint/eslint-plugin

What is @typescript-eslint/eslint-plugin?

The @typescript-eslint/eslint-plugin package is an ESLint plugin that contains a set of ESLint rules that are specifically designed for TypeScript code. It helps in identifying and reporting on patterns found in TypeScript code, and it can be used to enforce a wide range of coding standards and conventions.

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

Type-aware linting

This feature allows for rules that require type information. For example, the 'strict-boolean-expressions' rule ensures that boolean expressions are clear and error-free by considering the types involved in the expression.

/* eslint @typescript-eslint/strict-boolean-expressions: 'error' */
function isTruthy(value: any): boolean {
  return Boolean(value);
}

Code style enforcement

Enforces naming conventions for everything from variables to type parameters. This example enforces camelCase naming for variables.

/* eslint @typescript-eslint/naming-convention: ['error', { 'selector': 'variable', 'format': ['camelCase'] }] */
let myVariable = 1;

Accessibility checks

This feature requires functions and methods to explicitly define their return type to improve code readability and maintainability.

/* eslint @typescript-eslint/explicit-function-return-type: 'warn' */
function add(x: number, y: number) {
  return x + y;
}

Other packages similar to @typescript-eslint/eslint-plugin

eslint-plugin-react

This package provides linting rules for React and JSX. It's similar to @typescript-eslint/eslint-plugin in that it extends ESLint's capabilities to a specific language extension, but it focuses on React rather than TypeScript.

eslint-plugin-vue

This package is designed for linting Vue.js templates and scripts. Like @typescript-eslint/eslint-plugin, it provides additional rules that are specific to the Vue.js framework, complementing the standard ESLint rules.

eslint-plugin-import

This plugin provides a set of rules that help ensure proper imports, exports, and module structure. While it's not specific to TypeScript, it complements @typescript-eslint/eslint-plugin by enforcing best practices in module usage.

README

ESLint Plugin TypeScript

An ESLint plugin which provides lint rules for TypeScript codebases.

Getting Started

• You can find our Getting Started docs here
• You can find our FAQ / Troubleshooting docs here

These docs walk you through setting up ESLint, this plugin, and our parser. If you know what you're doing and just want to quick start, read on...

Quick-start

Installation

Make sure you have TypeScript and @typescript-eslint/parser installed:

$ yarn add -D typescript @typescript-eslint/parser
$ npm i --save-dev typescript @typescript-eslint/parser

Then install the plugin:

$ yarn add -D @typescript-eslint/eslint-plugin
$ npm i --save-dev @typescript-eslint/eslint-plugin

It is important that you use the same version number for @typescript-eslint/parser and @typescript-eslint/eslint-plugin.

Note: If you installed ESLint globally (using the -g flag) then you must also install @typescript-eslint/eslint-plugin globally.

Usage

Add @typescript-eslint/parser to the parser field and @typescript-eslint to the plugins section of your .eslintrc configuration file, then configure the rules you want to use under the rules section.

{
  "parser": "@typescript-eslint/parser",
  "plugins": ["@typescript-eslint"],
  "rules": {
    "@typescript-eslint/rule-name": "error"
  }
}

You can also enable all the recommended rules for our plugin. Add plugin:@typescript-eslint/recommended in extends:

{
  "extends": ["plugin:@typescript-eslint/recommended"]
}

Recommended Configs

You can also use eslint:recommended (the set of rules which are recommended for all projects by the ESLint Team) with this plugin:

{
  "extends": ["eslint:recommended", "plugin:@typescript-eslint/recommended"]
}

As of version 2 of this plugin, by design, none of the rules in the main recommended config require type-checking in order to run. This means that they are more lightweight and faster to run.

Some highly valuable rules require type-checking in order to be implemented correctly, however, so we provide an additional config you can extend from called recommended-requiring-type-checking. You would apply this in addition to the recommended configs previously mentioned, e.g.:

{
  "extends": [
    "eslint:recommended",
    "plugin:@typescript-eslint/recommended",
    "plugin:@typescript-eslint/recommended-requiring-type-checking"
  ]
}

Pro Tip: For larger codebases you may want to consider splitting our linting into two separate stages: 1. fast feedback rules which operate purely based on syntax (no type-checking), 2. rules which are based on semantics (type-checking).

You can read more about linting with type information here

Supported Rules

For the exhaustive list of supported rules, please see our website.

Contributing

See the contributing guide here.

Changelog

5.30.7 (2022-07-18)

Bug Fixes

• eslint-plugin: [no-inferrable] fix optional param to valid code (#5342) (98f6d5e)
• eslint-plugin: [no-unused-vars] highlight last write reference (#5267) (c3f199a)
• expose types supporting old versions of typescript (#5339) (4ba9bdb)
• scope-manager: allow visiting of constraint in infer type (#5331) (b2846a1)