no-explicit-any
Disallow the
any
type.
Extending "plugin:@typescript-eslint/recommended"
in an ESLint configuration enables this rule.
Some problems reported by this rule are automatically fixable by the --fix
ESLint command line option.
Some problems reported by this rule are manually fixable by editor suggestions.
The any
type in TypeScript is a dangerous "escape hatch" from the type system.
Using any
disables many type checking rules and is generally best used only as a last resort or when prototyping code.
This rule reports on explicit uses of the any
keyword as a type annotation.
TypeScript's
--noImplicitAny
compiler option prevents an impliedany
, but doesn't preventany
from being explicitly used the way this rule does.
module.exports = {
"rules": {
"@typescript-eslint/no-explicit-any": "warn"
}
};
Examples
- ❌ Incorrect
- ✅ Correct
const age: any = 'seventeen';
const ages: any[] = ['seventeen'];
const ages: Array<any> = ['seventeen'];
function greet(): any {}
function greet(): any[] {}
function greet(): Array<any> {}
function greet(): Array<Array<any>> {}
function greet(param: Array<any>): string {}
function greet(param: Array<any>): Array<any> {}
const age: number = 17;
const ages: number[] = [17];
const ages: Array<number> = [17];
function greet(): string {}
function greet(): string[] {}
function greet(): Array<string> {}
function greet(): Array<Array<string>> {}
function greet(param: Array<string>): string {}
function greet(param: Array<string>): Array<string> {}
Options
This rule accepts an options object with the following properties:
interface Options {
/**
* Whether to enable auto-fixing in which the `any` type is converted to the `unknown` type.
*/
fixToUnknown?: boolean;
/**
* Whether to ignore rest parameter arrays.
*/
ignoreRestArgs?: boolean;
}
const defaultOptions: Options = [
{ fixToUnknown: false, ignoreRestArgs: false },
];
ignoreRestArgs
A boolean to specify if arrays from the rest operator are considered okay. false
by default.
Examples of incorrect code for the { "ignoreRestArgs": false }
option:
/*eslint @typescript-eslint/no-explicit-any: ["error", { "ignoreRestArgs": false }]*/
function foo1(...args: any[]): void {}
function foo2(...args: readonly any[]): void {}
function foo3(...args: Array<any>): void {}
function foo4(...args: ReadonlyArray<any>): void {}
declare function bar(...args: any[]): void;
const baz = (...args: any[]) => {};
const qux = function (...args: any[]) {};
type Quux = (...args: any[]) => void;
type Quuz = new (...args: any[]) => void;
interface Grault {
(...args: any[]): void;
}
interface Corge {
new (...args: any[]): void;
}
interface Garply {
f(...args: any[]): void;
}
Examples of correct code for the { "ignoreRestArgs": true }
option:
/*eslint @typescript-eslint/no-explicit-any: ["error", { "ignoreRestArgs": true }]*/
function foo1(...args: any[]): void {}
function foo2(...args: readonly any[]): void {}
function foo3(...args: Array<any>): void {}
function foo4(...args: ReadonlyArray<any>): void {}
declare function bar(...args: any[]): void;
const baz = (...args: any[]) => {};
const qux = function (...args: any[]) {};
type Quux = (...args: any[]) => void;
type Quuz = new (...args: any[]) => void;
interface Grault {
(...args: any[]): void;
}
interface Corge {
new (...args: any[]): void;
}
interface Garply {
f(...args: any[]): void;
}
When Not To Use It
If an unknown type or a library without typings is used
and you want to be able to specify any
.
Related To
Further Reading
- TypeScript any type