FunctionReference

Napi::FunctionReference is a subclass of Napi::Reference, and
is equivalent to an instance of Napi::Reference<Napi::Function>. This means
that a Napi::FunctionReference holds a Napi::Function, and a
count of the number of references to that Napi::Function. When the count is
greater than 0, a Napi::FunctionReference is not eligible for garbage collection.
This ensures that the Function will remain accessible, even if the original
reference to it is no longer available.
Napi::FunctionReference allows the referenced JavaScript function object to be
called from a native add-on with two different methods: Call and MakeCallback.
See the documentation for Napi::Function for when Call should
be used instead of MakeCallback and vice-versa.

The Napi::FunctionReference class inherits its behavior from the Napi::Reference
class (for more info see: Napi::Reference).

Methods

Weak

Creates a "weak" reference to the value, in that the initial reference count is
set to 0.

static Napi::FunctionReference Napi::Weak(const Napi::Function& value);

• [in] value: The value which is to be referenced.

Returns the newly created reference.

Persistent

Creates a "persistent" reference to the value, in that the initial reference
count is set to 1.

static Napi::FunctionReference Napi::Persistent(const Napi::Function& value);

• [in] value: The value which is to be referenced.

Returns the newly created reference.

Constructor

Creates a new empty instance of Napi::FunctionReference.

Napi::FunctionReference::FunctionReference();

Constructor

Creates a new instance of the Napi::FunctionReference.

Napi::FunctionReference::FunctionReference(napi_env env, napi_ref ref);

• [in] env: The environment in which to construct the Napi::FunctionReference object.
• [in] ref: The N-API reference to be held by the Napi::FunctionReference.

Returns a newly created Napi::FunctionReference object.

New

Constructs a new instance by calling the constructor held by this reference.

Napi::Object Napi::FunctionReference::New(const std::initializer_list<napi_value>& args) const;

• [in] args: Initializer list of JavaScript values as napi_value representing
  the arguments of the contructor function.

Returns a new JavaScript object.

New

Constructs a new instance by calling the constructor held by this reference.

Napi::Object Napi::FunctionReference::New(const std::vector<napi_value>& args) const;

• [in] args: Vector of JavaScript values as napi_value representing the
  arguments of the constructor function.

Returns a new JavaScript object.

Call

Calls a referenced Javascript function from a native add-on.

Napi::Value Napi::FunctionReference::Call(const std::initializer_list<napi_value>& args) const;

• [in] args: Initializer list of JavaScript values as napi_value representing
  the arguments of the referenced function.

Returns a Napi::Value representing the JavaScript object returned by the referenced
function.

Call

Calls a referenced JavaScript function from a native add-on.

Napi::Value Napi::FunctionReference::Call(const std::vector<napi_value>& args) const;

• [in] args: Vector of JavaScript values as napi_value representing the
  arguments of the referenced function.

Returns a Napi::Value representing the JavaScript object returned by the referenced
function.

Call

Calls a referenced JavaScript function from a native add-on.

Napi::Value Napi::FunctionReference::Call(napi_value recv, const std::initializer_list<napi_value>& args) const;

• [in] recv: The this object passed to the referenced function when it's called.
• [in] args: Initializer list of JavaScript values as napi_value representing
  the arguments of the referenced function.

Returns a Napi::Value representing the JavaScript object returned by the referenced
function.

Call

Calls a referenced JavaScript function from a native add-on.

Napi::Value Napi::FunctionReference::Call(napi_value recv, const std::vector<napi_value>& args) const;

• [in] recv: The this object passed to the referenced function when it's called.
• [in] args: Vector of JavaScript values as napi_value representing the
  arguments of the referenced function.

Returns a Napi::Value representing the JavaScript object returned by the referenced
function.

Call

Calls a referenced JavaScript function from a native add-on.

Napi::Value Napi::FunctionReference::Call(napi_value recv, size_t argc, const napi_value* args) const;

• [in] recv: The this object passed to the referenced function when it's called.
• [in] argc: The number of arguments passed to the referenced function.
• [in] args: Array of JavaScript values as napi_value representing the
  arguments of the referenced function.

Returns a Napi::Value representing the JavaScript object returned by the referenced
function.

MakeCallback

Calls a referenced JavaScript function from a native add-on after an asynchronous
operation.

Napi::Value Napi::FunctionReference::MakeCallback(napi_value recv, const std::initializer_list<napi_value>& args, napi_async_context = nullptr) const;

• [in] recv: The this object passed to the referenced function when it's called.
• [in] args: Initializer list of JavaScript values as napi_value representing
  the arguments of the referenced function.
• [in] context: Context for the async operation that is invoking the callback.
  This should normally be a value previously obtained from Napi::AsyncContext.
  However nullptr is also allowed, which indicates the current async context
  (if any) is to be used for the callback.

Returns a Napi::Value representing the JavaScript object returned by the referenced
function.

MakeCallback

Calls a referenced JavaScript function from a native add-on after an asynchronous
operation.

Napi::Value Napi::FunctionReference::MakeCallback(napi_value recv, const std::vector<napi_value>& args, napi_async_context context = nullptr) const;

• [in] recv: The this object passed to the referenced function when it's called.
• [in] args: Vector of JavaScript values as napi_value representing the
  arguments of the referenced function.
• [in] context: Context for the async operation that is invoking the callback.
  This should normally be a value previously obtained from Napi::AsyncContext.
  However nullptr is also allowed, which indicates the current async context
  (if any) is to be used for the callback.

Returns a Napi::Value representing the JavaScript object returned by the referenced
function.

MakeCallback

Calls a referenced JavaScript function from a native add-on after an asynchronous
operation.

Napi::Value Napi::FunctionReference::MakeCallback(napi_value recv, size_t argc, const napi_value* args, napi_async_context context = nullptr) const;

• [in] recv: The this object passed to the referenced function when it's called.
• [in] argc: The number of arguments passed to the referenced function.
• [in] args: Array of JavaScript values as napi_value representing the
  arguments of the referenced function.
• [in] context: Context for the async operation that is invoking the callback.
  This should normally be a value previously obtained from Napi::AsyncContext.
  However nullptr is also allowed, which indicates the current async context
  (if any) is to be used for the callback.

Returns a Napi::Value representing the JavaScript object returned by the referenced
function.

Operator

Napi::Value operator ()(const std::initializer_list<napi_value>& args) const;

• [in] args: Initializer list of reference to JavaScript values as napi_value

Returns a Napi::Value representing the JavaScript value returned by the referenced
function.