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4.5.0 • Public • Published

ESLint Plugin TypeScript

An ESLint plugin which provides lint rules for TypeScript codebases.

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Getting Started

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...



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.


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"]

Note: Make sure to use eslint --ext .js,.ts since by default eslint will only search for .js files.

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 simply 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": [

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

Key: ✔️ = recommended, 🔧 = fixable, 💭 = requires type information

Name Description ✔️ 🔧 💭
@typescript-eslint/adjacent-overload-signatures Require that member overloads be consecutive ✔️
@typescript-eslint/array-type Requires using either T[] or Array<T> for arrays 🔧
@typescript-eslint/await-thenable Disallows awaiting a value that is not a Thenable ✔️ 💭
@typescript-eslint/ban-ts-comment Bans @ts-<directive> comments from being used or requires descriptions after directive ✔️
@typescript-eslint/ban-tslint-comment Bans // tslint:<rule-flag> comments from being used 🔧
@typescript-eslint/ban-types Bans specific types from being used ✔️ 🔧
@typescript-eslint/class-literal-property-style Ensures that literals on classes are exposed in a consistent style 🔧
@typescript-eslint/consistent-indexed-object-style Enforce or disallow the use of the record type 🔧
@typescript-eslint/consistent-type-assertions Enforces consistent usage of type assertions
@typescript-eslint/consistent-type-definitions Consistent with type definition either interface or type 🔧
@typescript-eslint/consistent-type-imports Enforces consistent usage of type imports 🔧
@typescript-eslint/explicit-function-return-type Require explicit return types on functions and class methods
@typescript-eslint/explicit-member-accessibility Require explicit accessibility modifiers on class properties and methods 🔧
@typescript-eslint/explicit-module-boundary-types Require explicit return and argument types on exported functions' and classes' public class methods ✔️
@typescript-eslint/member-delimiter-style Require a specific member delimiter style for interfaces and type literals 🔧
@typescript-eslint/member-ordering Require a consistent member declaration order
@typescript-eslint/method-signature-style Enforces using a particular method signature syntax. 🔧
@typescript-eslint/naming-convention Enforces naming conventions for everything across a codebase 💭
@typescript-eslint/no-base-to-string Requires that .toString() is only called on objects which provide useful information when stringified 💭
@typescript-eslint/no-confusing-non-null-assertion Disallow non-null assertion in locations that may be confusing 🔧
@typescript-eslint/no-dynamic-delete Disallow the delete operator with computed key expressions 🔧
@typescript-eslint/no-empty-interface Disallow the declaration of empty interfaces ✔️ 🔧
@typescript-eslint/no-explicit-any Disallow usage of the any type ✔️ 🔧
@typescript-eslint/no-extra-non-null-assertion Disallow extra non-null assertion ✔️ 🔧
@typescript-eslint/no-extraneous-class Forbids the use of classes as namespaces
@typescript-eslint/no-floating-promises Requires Promise-like values to be handled appropriately ✔️ 💭
@typescript-eslint/no-for-in-array Disallow iterating over an array with a for-in loop ✔️ 💭
@typescript-eslint/no-implicit-any-catch Disallow usage of the implicit any type in catch clauses 🔧
@typescript-eslint/no-implied-eval Disallow the use of eval()-like methods ✔️ 💭
@typescript-eslint/no-inferrable-types Disallows explicit type declarations for variables or parameters initialized to a number, string, or boolean ✔️ 🔧
@typescript-eslint/no-invalid-void-type Disallows usage of void type outside of generic or return types
@typescript-eslint/no-misused-new Enforce valid definition of new and constructor ✔️
@typescript-eslint/no-misused-promises Avoid using promises in places not designed to handle them ✔️ 💭
@typescript-eslint/no-namespace Disallow the use of custom TypeScript modules and namespaces ✔️
@typescript-eslint/no-non-null-asserted-optional-chain Disallows using a non-null assertion after an optional chain expression ✔️
@typescript-eslint/no-non-null-assertion Disallows non-null assertions using the ! postfix operator ✔️
@typescript-eslint/no-parameter-properties Disallow the use of parameter properties in class constructors
@typescript-eslint/no-require-imports Disallows invocation of require()
@typescript-eslint/no-this-alias Disallow aliasing this ✔️
@typescript-eslint/no-throw-literal Disallow throwing literals as exceptions 💭
@typescript-eslint/no-type-alias Disallow the use of type aliases
@typescript-eslint/no-unnecessary-boolean-literal-compare Flags unnecessary equality comparisons against boolean literals 🔧 💭
@typescript-eslint/no-unnecessary-condition Prevents conditionals where the type is always truthy or always falsy 🔧 💭
@typescript-eslint/no-unnecessary-qualifier Warns when a namespace qualifier is unnecessary 🔧 💭
@typescript-eslint/no-unnecessary-type-arguments Enforces that type arguments will not be used if not required 🔧 💭
@typescript-eslint/no-unnecessary-type-assertion Warns if a type assertion does not change the type of an expression ✔️ 🔧 💭
@typescript-eslint/no-unsafe-assignment Disallows assigning any to variables and properties ✔️ 💭
@typescript-eslint/no-unsafe-call Disallows calling an any type value ✔️ 💭
@typescript-eslint/no-unsafe-member-access Disallows member access on any typed variables ✔️ 💭
@typescript-eslint/no-unsafe-return Disallows returning any from a function ✔️ 💭
@typescript-eslint/no-var-requires Disallows the use of require statements except in import statements ✔️
@typescript-eslint/prefer-as-const Prefer usage of as const over literal type ✔️ 🔧
@typescript-eslint/prefer-enum-initializers Prefer initializing each enums member value
@typescript-eslint/prefer-for-of Prefer a ‘for-of’ loop over a standard ‘for’ loop if the index is only used to access the array being iterated
@typescript-eslint/prefer-function-type Use function types instead of interfaces with call signatures 🔧
@typescript-eslint/prefer-includes Enforce includes method over indexOf method 🔧 💭
@typescript-eslint/prefer-literal-enum-member Require that all enum members be literal values to prevent unintended enum member name shadow issues
@typescript-eslint/prefer-namespace-keyword Require the use of the namespace keyword instead of the module keyword to declare custom TypeScript modules ✔️ 🔧
@typescript-eslint/prefer-nullish-coalescing Enforce the usage of the nullish coalescing operator instead of logical chaining 💭
@typescript-eslint/prefer-optional-chain Prefer using concise optional chain expressions instead of chained logical ands
@typescript-eslint/prefer-readonly Requires that private members are marked as readonly if they're never modified outside of the constructor 🔧 💭
@typescript-eslint/prefer-readonly-parameter-types Requires that function parameters are typed as readonly to prevent accidental mutation of inputs 💭
@typescript-eslint/prefer-reduce-type-parameter Prefer using type parameter when calling Array#reduce instead of casting 🔧 💭
@typescript-eslint/prefer-regexp-exec Enforce that RegExp#exec is used instead of String#match if no global flag is provided ✔️ 💭
@typescript-eslint/prefer-string-starts-ends-with Enforce the use of String#startsWith and String#endsWith instead of other equivalent methods of checking substrings 🔧 💭
@typescript-eslint/prefer-ts-expect-error Recommends using @ts-expect-error over @ts-ignore 🔧
@typescript-eslint/promise-function-async Requires any function or method that returns a Promise to be marked async 💭
@typescript-eslint/require-array-sort-compare Requires Array#sort calls to always provide a compareFunction 💭
@typescript-eslint/restrict-plus-operands When adding two variables, operands must both be of type number or of type string ✔️ 💭
@typescript-eslint/restrict-template-expressions Enforce template literal expressions to be of string type ✔️ 💭
@typescript-eslint/strict-boolean-expressions Restricts the types allowed in boolean expressions 💭
@typescript-eslint/switch-exhaustiveness-check Exhaustiveness checking in switch with union type 💭
@typescript-eslint/triple-slash-reference Sets preference level for triple slash directives versus ES6-style import declarations ✔️
@typescript-eslint/type-annotation-spacing Require consistent spacing around type annotations 🔧
@typescript-eslint/typedef Requires type annotations to exist
@typescript-eslint/unbound-method Enforces unbound methods are called with their expected scope ✔️ 💭
@typescript-eslint/unified-signatures Warns for any two overloads that could be unified into one by using a union or an optional/rest parameter

Extension Rules

In some cases, ESLint provides a rule itself, but it doesn't support TypeScript syntax; either it crashes, or it ignores the syntax, or it falsely reports against it. In these cases, we create what we call an extension rule; a rule within our plugin that has the same functionality, but also supports TypeScript.

Key: ✔️ = recommended, 🔧 = fixable, 💭 = requires type information

Name Description ✔️ 🔧 💭
@typescript-eslint/brace-style Enforce consistent brace style for blocks 🔧
@typescript-eslint/comma-dangle Require or disallow trailing comma 🔧
@typescript-eslint/comma-spacing Enforces consistent spacing before and after commas 🔧
@typescript-eslint/default-param-last Enforce default parameters to be last
@typescript-eslint/dot-notation enforce dot notation whenever possible 🔧 💭
@typescript-eslint/func-call-spacing Require or disallow spacing between function identifiers and their invocations 🔧
@typescript-eslint/indent Enforce consistent indentation 🔧
@typescript-eslint/init-declarations require or disallow initialization in variable declarations
@typescript-eslint/keyword-spacing Enforce consistent spacing before and after keywords 🔧
@typescript-eslint/lines-between-class-members Require or disallow an empty line between class members 🔧
@typescript-eslint/no-array-constructor Disallow generic Array constructors ✔️ 🔧
@typescript-eslint/no-dupe-class-members Disallow duplicate class members
@typescript-eslint/no-duplicate-imports Disallow duplicate imports
@typescript-eslint/no-empty-function Disallow empty functions ✔️
@typescript-eslint/no-extra-parens Disallow unnecessary parentheses 🔧
@typescript-eslint/no-extra-semi Disallow unnecessary semicolons ✔️ 🔧
@typescript-eslint/no-invalid-this disallow this keywords outside of classes or class-like objects
@typescript-eslint/no-loop-func Disallow function declarations that contain unsafe references inside loop statements
@typescript-eslint/no-loss-of-precision Disallow literal numbers that lose precision
@typescript-eslint/no-magic-numbers Disallow magic numbers
@typescript-eslint/no-redeclare Disallow variable redeclaration
@typescript-eslint/no-shadow Disallow variable declarations from shadowing variables declared in the outer scope
@typescript-eslint/no-unused-expressions Disallow unused expressions
@typescript-eslint/no-unused-vars Disallow unused variables ✔️
@typescript-eslint/no-use-before-define Disallow the use of variables before they are defined
@typescript-eslint/no-useless-constructor Disallow unnecessary constructors
@typescript-eslint/quotes Enforce the consistent use of either backticks, double, or single quotes 🔧
@typescript-eslint/require-await Disallow async functions which have no await expression ✔️ 💭
@typescript-eslint/return-await Enforces consistent returning of awaited values 🔧 💭
@typescript-eslint/semi Require or disallow semicolons instead of ASI 🔧
@typescript-eslint/space-before-function-paren Enforces consistent spacing before function parenthesis 🔧


See the contributing guide here.


npm i @typescript-eslint/eslint-plugin

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