> For the complete documentation index, see [llms.txt](https://docs.angular-package.dev/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.angular-package.dev/text/wrapper/wrap/generic-type-variables.md).

# Generic type variables

### `Wrap<Opening, ...>`

**`Opening extends string`**

​A generic type variable constrained by the [`string`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String), by default of the value captured from the provided `opening` indicates the opening type of a new [`Wrap`](/text/wrapper/wrap.md) instance.

### `Wrap<..., Closing>`

**`Closing extends string`**

​A generic type variable constrained by the [`string`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String), by default of the value captured from the provided `closing` indicates the closing type of a new [`Wrap`](/text/wrapper/wrap.md) instance.

{% code title="wrap.class.ts" %}

```typescript
class Wrap<
  Opening extends string = string,
  Closing extends string = string
> extends String ...
```

{% endcode %}