napi define class

napi_status napi_define_class(napi_env env,
                              const char* utf8name,
                              size_t length,
                              napi_callback constructor,
                              void* data,
                              size_t property_count,
                              const napi_property_descriptor* properties,
                              napi_value* result);

• [in] env: The environment that the API is invoked under.
• [in] utf8name: Name of the JavaScript constructor function; When wrapping a C++ class, we recommend for clarity that this name be the same as that of the C++ class.
• [in] length: The length of the utf8name in bytes, or NAPI_AUTO_LENGTH if it is null-terminated.
• [in] constructor: Callback function that handles constructing instances of the class. When wrapping a C++ class, this method must be a static member with the [napi_callback][] signature. A C++ class constructor cannot be used. [napi_callback][] provides more details.
• [in] data: Optional data to be passed to the constructor callback as the data property of the callback info.
• [in] property_count: Number of items in the properties array argument.
• [in] properties: Array of property descriptors describing static and instance data properties, accessors, and methods on the class See napi_property_descriptor.
• [out] result: A napi_value representing the constructor function for the class.

Returns napi_ok if the API succeeded.

Defines a JavaScript class, including:

• A JavaScript constructor function that has the class name. When wrapping a corresponding C++ class, the callback passed via constructor can be used to instantiate a new C++ class instance, which can then be placed inside the JavaScript object instance being constructed using [napi_wrap][].
• Properties on the constructor function whose implementation can call corresponding static data properties, accessors, and methods of the C++ class (defined by property descriptors with the napi_static attribute).
• Properties on the constructor function’s prototype object. When wrapping a C++ class, non-static data properties, accessors, and methods of the C++ class can be called from the static functions given in the property descriptors without the napi_static attribute after retrieving the C++ class instance placed inside the JavaScript object instance by using [napi_unwrap][].

When wrapping a C++ class, the C++ constructor callback passed via constructor should be a static method on the class that calls the actual class constructor, then wraps the new C++ instance in a JavaScript object, and returns the wrapper object. See [napi_wrap][] for details.

The JavaScript constructor function returned from [napi_define_class][] is often saved and used later to construct new instances of the class from native code, and/or to check whether provided values are instances of the class. In that case, to prevent the function value from being garbage-collected, a strong persistent reference to it can be created using [napi_create_reference][], ensuring that the reference count is kept >= 1.

Any non-NULL data which is passed to this API via the data parameter or via the data field of the napi_property_descriptor array items can be associated with the resulting JavaScript constructor (which is returned in the result parameter) and freed whenever the class is garbage-collected by passing both the JavaScript function and the data to [napi_add_finalizer][].