es-toolkit/docs/reference/predicate/isNull.md

# isNull

Checks if the given value is null.

This function tests whether the provided value is strictly equal to `null`.
It returns `true` if the value is `null`, and `false` otherwise.

This function can also serve as a type predicate in TypeScript, narrowing the type of the argument to `null`.

## Signature

```typescript
function isNull(x: unknown): x is null;
```

### Parameters

- `x` (`unknown`): The value to test if it is null.

### Returns

(`x is null`): True if the value is null, false otherwise.

## Examples

```typescript
const value1 = null;
const value2 = undefined;
const value3 = 42;

console.log(isNull(value1)); // true
console.log(isNull(value2)); // false
console.log(isNull(value3)); // false
```