# unavailable

Chooses fallback execution or an error when the requested engine is unavailable.

Canonical: https://grid.syidax.com/docs/options/unavailable/

<a id="meaning"></a>

## What does this API do?

Chooses fallback execution or an error when the requested engine is unavailable.

Behavior when the Pro engine is unavailable. The Standard JS engine is Free.

<a id="contract"></a>

## Exact input and result types

```typescript
unavailable: GridUnavailableBehaviour
```

| Item | Value |
| --- | --- |
| JavaScript name | unavailable |
| HTML attribute | unavailable |
| Default | 'fallback' |
| Input type | GridUnavailableBehaviour |

<a id="usage"></a>

## Usage flow

Set this on a property of the Grid element. In HTML, you can also use the unavailable attribute. Pass arrays, objects, and callbacks through JavaScript, and use new arrays or objects when applying changes.

<a id="types"></a>

## Read related types

- [GridUnavailableBehaviour](https://grid.syidax.com/docs/types/GridUnavailableBehaviour.md)

<a id="recipes"></a>

## Feature explanations and examples

- [Choose a processing engine](https://grid.syidax.com/docs/features/wasm-acceleration.md) — Pro engines accelerate supported sorting, filtering, and aggregation. The actual execution path depends on the browser, package, license, and current feature combination.