A Napi::Object can be assigned properties via its DefineProperty and DefineProperties functions, which take PropertyDescriptor(s) as their parameters. The Napi::PropertyDescriptor can contain either values or functions, which are then assigned to the Napi::Object. Note that a single instance of a Napi::PropertyDescriptor class can only contain either one value, or at most two functions. PropertyDescriptors can only be created through the class methods Accessor, Function, or Value, each of which return a new static instance of a Napi::PropertyDescriptor.
#include <napi.h>
using namespace Napi;
Value TestGetter(const CallbackInfo& info) {
return Boolean::New(info.Env(), testValue);
}
void TestSetter(const CallbackInfo& info) {
testValue = info[0].As<Boolean>();
}
Value TestFunction(const CallbackInfo& info) {
return Boolean::New(info.Env(), true);
}
Void Init(Env env) {
// Create an object.
Object obj = Object::New(env);
// Accessor
PropertyDescriptor pd1 = PropertyDescriptor::Accessor<TestGetter>("pd1");
PropertyDescriptor pd2 =
PropertyDescriptor::Accessor<TestGetter, TestSetter>("pd2");
// Function
PropertyDescriptor pd3 = PropertyDescriptor::Function(env,
"function",
TestFunction);
// Value
Boolean true_bool = Boolean::New(env, true);
PropertyDescriptor pd4 =
PropertyDescriptor::Value("boolean value",
Napi::Boolean::New(env, true),
napi_writable);
// Assign properties to the object.
obj.DefineProperties({pd1, pd2, pd3, pd4});
}using GetterCallback = Napi::Value (*)(const Napi::CallbackInfo& info);This is the signature of a getter function to be passed as a template parameter
to PropertyDescriptor::Accessor.
using SetterCallback = void (*)(const Napi::CallbackInfo& info);This is the signature of a setter function to be passed as a template parameter
to PropertyDescriptor::Accessor.
Napi::PropertyDescriptor::PropertyDescriptor (napi_property_descriptor desc);[in] desc: A PropertyDescriptor that is needed in order to create another PropertyDescriptor.
template <Napi::PropertyDescriptor::GetterCallback Getter>
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Accessor (___ name,
napi_property_attributes attributes = napi_default,
void* data = nullptr);[template] Getter: A getter function.[in] attributes: Potential attributes for the getter function.[in] data: A pointer to data of any type, default is a null pointer.
Returns a PropertyDescriptor that contains a read-only property.
The name of the property can be any of the following types:
const char*const std::string &napi_value valueNapi::Name
template <
Napi::PropertyDescriptor::GetterCallback Getter,
Napi::PropertyDescriptor::SetterCallback Setter>
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Accessor (___ name,
napi_property_attributes attributes = napi_default,
void* data = nullptr);[template] Getter: A getter function.[template] Setter: A setter function.[in] attributes: Potential attributes for the getter function.[in] data: A pointer to data of any type, default is a null pointer.
Returns a PropertyDescriptor that contains a read-write property.
The name of the property can be any of the following types:
const char*const std::string &napi_value valueNapi::Name
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Accessor (___ name,
Getter getter,
napi_property_attributes attributes = napi_default,
void *data = nullptr);[in] name: The name used for the getter function.[in] getter: A getter function.[in] attributes: Potential attributes for the getter function.[in] data: A pointer to data of any type, default is a null pointer.
Returns a PropertyDescriptor that contains a function.
The name of the property can be any of the following types:
const char*const std::string &napi_value valueNapi::Name
The above signature is deprecated. It will result in a memory leak if used.
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Accessor (
Napi::Env env,
Napi::Object object,
___ name,
Getter getter,
napi_property_attributes attributes = napi_default,
void *data = nullptr);[in] env: The environment in which to create this accessor.[in] object: The object on which the accessor will be defined.[in] name: The name used for the getter function.[in] getter: A getter function.[in] attributes: Potential attributes for the getter function.[in] data: A pointer to data of any type, default is a null pointer.
Returns a Napi::PropertyDescriptor that contains a Getter accessor.
The name of the property can be any of the following types:
const char*const std::string &Napi::Name
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Accessor (___ name,
Getter getter,
Setter setter,
napi_property_attributes attributes = napi_default,
void *data = nullptr);[in] name: The name of the getter and setter function.[in] getter: The getter function.[in] setter: The setter function.[in] attributes: Potential attributes for the getter function.[in] data: A pointer to data of any type, default is a null pointer.
Returns a Napi::PropertyDescriptor that contains a Getter and Setter function.
The name of the property can be any of the following types:
const char*const std::string &napi_value valueNapi::Name
The above signature is deprecated. It will result in a memory leak if used.
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Accessor (
Napi::Env env,
Napi::Object object,
___ name,
Getter getter,
Setter setter,
napi_property_attributes attributes = napi_default,
void *data = nullptr);[in] env: The environment in which to create this accessor.[in] object: The object on which the accessor will be defined.[in] name: The name of the getter and setter function.[in] getter: The getter function.[in] setter: The setter function.[in] attributes: Potential attributes for the getter function.[in] data: A pointer to data of any type, default is a null pointer.
Returns a Napi::PropertyDescriptor that contains a Getter and Setter function.
The name of the property can be any of the following types:
const char*const std::string &Napi::Name
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Function (___ name,
Callable cb,
napi_property_attributes attributes = napi_default,
void *data = nullptr);[in] name: The name of the Callable function.[in] cb: The function[in] attributes: Potential attributes for the getter function.[in] data: A pointer to data of any type, default is a null pointer.
Returns a Napi::PropertyDescriptor that contains a callable Napi::Function.
The name of the property can be any of the following types:
const char*const std::string &napi_value valueNapi::Name
The above signature is deprecated. It will result in a memory leak if used.
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Function (
Napi::Env env,
___ name,
Callable cb,
napi_property_attributes attributes = napi_default,
void *data = nullptr);[in] env: The environment in which to create this accessor.[in] name: The name of the Callable function.[in] cb: The function[in] attributes: Potential attributes for the getter function.[in] data: A pointer to data of any type, default is a null pointer.
Returns a Napi::PropertyDescriptor that contains a callable Napi::Function.
The name of the property can be any of the following types:
const char*const std::string &Napi::Name
static Napi::PropertyDescriptor Napi::PropertyDescriptor::Value (___ name,
napi_value value,
napi_property_attributes attributes = napi_default);The name of the property can be any of the following types:
const char*const std::string &napi_value valueNapi::Name
napi_property_attributes are flags used to indicate to JavaScript certain permissions that the property is meant to have. The following are the flag options:
- napi_default,
- napi_writable,
- napi_enumerable,
- napi_configurable For more information on the flags and on napi_property_attributes, please read the documentation here.