# ArrayBuffer

Class `Napi::ArrayBuffer` inherits from class [`Napi::Object`][].

The `Napi::ArrayBuffer` class corresponds to the
[JavaScript `ArrayBuffer`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer)
class.

## Methods

### New

Allocates a new `Napi::ArrayBuffer` instance with a given length.

```cpp
static Napi::ArrayBuffer Napi::ArrayBuffer::New(napi_env env, size_t byteLength);
```

- `[in] env`: The environment in which to create the `Napi::ArrayBuffer` instance.
- `[in] byteLength`: The length to be allocated, in bytes.

Returns a new `Napi::ArrayBuffer` instance.

### New

Wraps the provided external data into a new `Napi::ArrayBuffer` instance.

The `Napi::ArrayBuffer` instance does not assume ownership for the data and
expects it to be valid for the lifetime of the instance. Since the
`Napi::ArrayBuffer` is subject to garbage collection this overload is only
suitable for data which is static and never needs to be freed.

```cpp
static Napi::ArrayBuffer Napi::ArrayBuffer::New(napi_env env, void* externalData, size_t byteLength);
```

- `[in] env`: The environment in which to create the `Napi::ArrayBuffer` instance.
- `[in] externalData`: The pointer to the external data to wrap.
- `[in] byteLength`: The length of the `externalData`, in bytes.

Returns a new `Napi::ArrayBuffer` instance.

### New

Wraps the provided external data into a new `Napi::ArrayBuffer` instance.

The `Napi::ArrayBuffer` instance does not assume ownership for the data and
expects it to be valid for the lifetime of the instance. The data can only be
freed once the `finalizeCallback` is invoked to indicate that the
`Napi::ArrayBuffer` has been released.

```cpp
template <typename Finalizer>
static Napi::ArrayBuffer Napi::ArrayBuffer::New(napi_env env,
                       void* externalData,
                       size_t byteLength,
                       Finalizer finalizeCallback);
```

- `[in] env`: The environment in which to create the `Napi::ArrayBuffer` instance.
- `[in] externalData`: The pointer to the external data to wrap.
- `[in] byteLength`: The length of the `externalData`, in bytes.
- `[in] finalizeCallback`: A function to be called when the `Napi::ArrayBuffer` is
  destroyed. It must implement `operator()`, accept a `void*` (which is the
  `externalData` pointer), and return `void`.

Returns a new `Napi::ArrayBuffer` instance.

### New

Wraps the provided external data into a new `Napi::ArrayBuffer` instance.

The `Napi::ArrayBuffer` instance does not assume ownership for the data and expects it
to be valid for the lifetime of the instance. The data can only be freed once
the `finalizeCallback` is invoked to indicate that the `Napi::ArrayBuffer` has been
released.

```cpp
template <typename Finalizer, typename Hint>
static Napi::ArrayBuffer Napi::ArrayBuffer::New(napi_env env,
                       void* externalData,
                       size_t byteLength,
                       Finalizer finalizeCallback,
                       Hint* finalizeHint);
```

- `[in] env`: The environment in which to create the `Napi::ArrayBuffer` instance.
- `[in] externalData`: The pointer to the external data to wrap.
- `[in] byteLength`: The length of the `externalData`, in bytes.
- `[in] finalizeCallback`: The function to be called when the `Napi::ArrayBuffer` is
  destroyed. It must implement `operator()`, accept a `void*` (which is the
  `externalData` pointer) and `Hint*`, and return `void`.
- `[in] finalizeHint`: The hint to be passed as the second parameter of the
  finalize callback.

Returns a new `Napi::ArrayBuffer` instance.

### Constructor

Initializes an empty instance of the `Napi::ArrayBuffer` class.

```cpp
Napi::ArrayBuffer::ArrayBuffer();
```

### Constructor

Initializes a wrapper instance of an existing `Napi::ArrayBuffer` object.

```cpp
Napi::ArrayBuffer::ArrayBuffer(napi_env env, napi_value value);
```

- `[in] env`: The environment in which to create the `Napi::ArrayBuffer` instance.
- `[in] value`: The `Napi::ArrayBuffer` reference to wrap.

### ByteLength

```cpp
size_t Napi::ArrayBuffer::ByteLength() const;
```

Returns the length of the wrapped data, in bytes.

### Data

```cpp
void* Napi::ArrayBuffer::Data() const;
```

Returns a pointer the wrapped data.

[`Napi::Object`]: ./object.md