eslint-plugin-redundant-undefined

> Forbids optional parameters to include an explicit undefined in their type and requires to use undefined in optional properties.

  !GitHub Workflow Status (with branch)  

Installation

``
$ npm i eslint-plugin-redundant-undefined @typescript-eslint/parser --save-dev
`

Usage

Add redundant-undefined to the plugins section of your .eslintrc configuration file. You can omit the eslint-plugin- prefix:

`json
{
"parser": "@typescript-eslint/parser",
"plugins": ["redundant-undefined"]
}
`

Then configure the rules you want to use under the rules section.

`json
{
"rules": {
"redundant-undefined/redundant-undefined": "error"
}
}
`

Rule Details

- Avoid explicitly specifying undefined as a type for a parameter/property which is already optional

$3

- followExactOptionalPropertyTypes - Requires explicitly specifying undefined as a type for a parameter which is already optional., this provides the correct semantics for people who have exactOptionalPropertyType: true

$3

Examples of incorrect code:

`ts
function f(s?: undefined | string): void {}

function f(s?: number | undefined | string): void {}

interface I {
a?: string | undefined;
}

class C {
a?: string | undedined;
}
`

Examples of correct code:

`ts
function f(s?: string): void {}

interface I {
a?: string;
}

interface I {
a?: any;
}

class C {
a?: string;
}
`

Examples of incorrect code for the { "followExactOptionalPropertyTypes": true }:

`ts
interface I {
p?: string;
}

class C {
private p?: number;
}

abstract class C {
abstract p?: string;
}
`

Examples of correct code for the { "followExactOptionalPropertyTypes": true }:

`ts
interface I {
p?: string | undefined;
}

interface I {
p?: any;
}

class C {
private p?: number | undefined;
}

abstract class C {
abstract p?: string | undefined;
}
``

License and Copyright

This software is released under the terms of the MIT license.