js-utils/docs/api/js-utils.mustexist.md

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[Home](./index.md) &gt; [@apextoaster/js-utils](./js-utils.md) &gt; [mustExist](./js-utils.mustexist.md)

## mustExist() function

Assert that a variable is not `None` and return the value. Throw if it is `None`<!-- -->.

<b>Signature:</b>

```typescript
export declare function mustExist<T>(val: Maybe<T>, err?: string): T;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  val | [Maybe](./js-utils.maybe.md)<!-- -->&lt;T&gt; |  |
|  err | string |  |

<b>Returns:</b>

T

val

## Exceptions

NotFoundError