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# cancel()

The **`cancel()`** method of the `ReadableStreamBYOBReader` interface returns a `Promise` that resolves when the stream is canceled.
Calling this method signals a loss of interest in the stream by a consumer.

> **Note:** If the reader is active, the `cancel()` method behaves the same as that for the associated stream (`ReadableStream.cancel()`).

## Syntax

```js
cancel()
cancel(reason)
```

### Parameters

- `reason` __optional__
  - : A human-readable reason for the cancellation. The underlying source may or may not use it.

### Return value

A `Promise`, which fulfills with the value given in the `reason` parameter.

### Exceptions

- `TypeError`
  - : The source object is not a `ReadableStreamBYOBReader`, or the stream has no owner.
