The Napi::External template class implements the ability to create a Napi::Value object with arbitrary C++ data. It is the user's responsibility to manage the memory for the arbitrary C++ data.
Napi::External objects can be created with an optional Finalizer function and optional Hint value. The Finalizer function, if specified, is called when your Napi::External object is released by Node's garbage collector. It gives your code the opportunity to free any dynamically created data. If you specify a Hint value, it is passed to your Finalizer function.
cpp
template <typename T>
static Napi::External Napi::External::New(napi_env env, T* data);
[in] env: The napi_env environment in which to construct the Napi::External object.[in] data: The arbitrary C++ data to be held by the Napi::External object.Returns the created Napi::External<T> object.
cpp
template <typename T>
static Napi::External Napi::External::New(napi_env env,
T* data,
Finalizer finalizeCallback);
[in] env: The napi_env environment in which to construct the Napi::External object.[in] data: The arbitrary C++ data to be held by the Napi::External object.[in] finalizeCallback: A function called when the Napi::External object is released by the garbage collector accepting a T* and returning void.Returns the created Napi::External<T> object.
cpp
template <typename T>
static Napi::External Napi::External::New(napi_env env,
T* data,
Finalizer finalizeCallback,
Hint* finalizeHint);
[in] env: The napi_env environment in which to construct the Napi::External object.[in] data: The arbitrary C++ data to be held by the Napi::External object.[in] finalizeCallback: A function called when the Napi::External object is released by the garbage collector accepting T and Hint parameters and returning void.[in] finalizeHint: A hint value passed to the finalizeCallback function.Returns the created Napi::External<T> object.
cpp
T* Napi::External::Data() const;
Returns a pointer to the arbitrary C++ data held by the Napi::External object.