---
url: /reference/OutputOptions.extend.md
---
# extend

* **Type**: `boolean`
* **Optional**

Whether to extend the global variable defined by the [`name`](./OutputOptions.name) option in `umd` or `iife` [formats](./OutputOptions.format).

When `true`, the global variable will be defined as `global.name = global.name || {}`.
When `false`, the global defined by name will be overwritten like `global.name = {}`.

## Default

```ts
false
```