description: 'Disallow unary expressions for number string | null or string | undefined or number | null or number | undefined on if statements'

Installation

npm i --save-dev eslint-plugin-no-unary-expression
or
yarn add --dev eslint-plugin-no-unary-expression

Usage

In your .eslintrc add eslint-plugin-no-unary-expression to the plugin section.

{
  "plugins": ["eslint-plugin-no-unary-expression"],
  "rules": {
    "no-unary-expression/no-unary-expression": 2
  }
}

Rule Details

The following expressions are checked:

• number | null
• number | undefined
• string | null
• string | undefined

Examples of code for this rule:

❌ Incorrect

let a = [1,2,3];
let b = a.find(item => item === 7);
if (!b) {}

✅ Correct

let a = [1,2,3];
let b = a.find(item => item === 7);
if (b !== undefined) {}