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# ReadableStreamDefaultReader()

The **`ReadableStreamDefaultReader()`**
constructor creates and returns a `ReadableStreamDefaultReader` object
instance.

## Syntax

```js
new ReadableStreamDefaultReader(stream)
```

### Parameters

- `stream`
  - : The `ReadableStream` to be read.

### Return value

An instance of the `ReadableStreamDefaultReader` object.

### Exceptions

- `TypeError`
  - : Thrown if the supplied `stream` parameter is not a `ReadableStream`,
    or it is already locked for reading by another reader.
