import { Meta } from '@storybook/addon-docs/blocks'

<Meta title='@dxtmisha/en/functional-basic/Functions/isNull - Check for null or undefined'/>

# `isNull`

An explicit, stringent utility focused entirely on confirming if a presented variable strictly equals either `null` or `undefined`.

Distinguished from a conventional negative falsy check like `!value` (which intercepts valid zeroes `0`, vacuous strings `''`, and `false` toggles), this function deliberately sidesteps those values, honing in flawlessly on absent definitions.

**Parameters:**
- `value: T` — Any inclusive subject variable requested to be verified.

**Returns:**
`boolean` — Returns `true` uniformly whenever confronted with a raw `null` or an isolated `undefined` marker. It likewise fulfills the responsibility as a TypeScript type guard, securely minimizing the scope to `Undefined` (`null | undefined`).

```typescript
import { isNull } from '@dxtmisha/functional-basic'

console.log(isNull(null)) // true
console.log(isNull(undefined)) // true

// Routine falsy traps revert as false logically
console.log(isNull(0)) // false
console.log(isNull('')) // false
console.log(isNull(false)) // false
```
