--- description: 'Disallow unary expressions for number string | null or string | undefined or number | null or number | undefined on if statements' ---
npm install eslint-plugin-no-unary-expression---
description: 'Disallow unary expressions for number string | null or string | undefined or number | null or number | undefined on if statements'
---
npm i --save-dev eslint-plugin-no-unary-expression yarn add --dev eslint-plugin-no-unary-expressionIn your .eslintrc add eslint-plugin-no-unary-expression to the plugin section.
``json`
{
"plugins": ["eslint-plugin-no-unary-expression"],
"rules": {
"no-unary-expression/no-unary-expression": 2
}
}
The following expressions are checked:
- number | null
- number | undefined
- string | null
- string | undefined
Examples of code for this rule:
`ts`
let a = [1,2,3];
let b = a.find(item => item === 7);
if (!b) {}
`ts``
let a = [1,2,3];
let b = a.find(item => item === 7);
if (b !== undefined) {}