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handle_scope.md

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HandleScope

The HandleScope class is used to manage the lifetime of object handles which are created through the use of node-addon-api. These handles keep an object alive in the heap in order to ensure that the objects are not collected while native code is using them. A handle may be created when any new node-addon-api Value or one of its subclasses is created or returned. For more details refer to the section titled Object lifetime management.

Methods

Constructor

Creates a new handle scope on the stack.

Napi::HandleScope::HandleScope(Napi::Env env);
  • [in] env: The environment in which to construct the Napi::HandleScope object.

Returns a new Napi::HandleScope

Constructor

Creates a new handle scope on the stack.

Napi::HandleScope::HandleScope(Napi::Env env, Napi::HandleScope scope);
  • [in] env: Napi::Env in which the scope passed in was created.
  • [in] scope: pre-existing Napi::HandleScope.

Returns a new Napi::HandleScope instance which wraps the napi_handle_scope handle passed in. This can be used to mix usage of the C Node-API and node-addon-api.

operator Napi::HandleScope::napi_handle_scope() const

Returns the Node-API napi_handle_scope wrapped by the Napi::EscapableHandleScope object. This can be used to mix usage of the C Node-API and node-addon-api by allowing the class to be used be converted to a napi_handle_scope.

Destructor

Napi::HandleScope::~HandleScope();

Deletes the Napi::HandleScope instance and allows any objects/handles created in the scope to be collected by the garbage collector. There is no guarantee as to when the garbage collector will do this.

Env

Napi::Env Napi::HandleScope::Env() const;

Returns the Napi::Env associated with the Napi::HandleScope.

Example

for (int i = 0; i < LOOP_MAX; i++) {
  Napi::HandleScope scope(info.Env());
  std::string name = std::string("inner-scope") + std::to_string(i);
  Napi::Value newValue = Napi::String::New(info.Env(), name.c_str());
  // do something with newValue
};

For more details refer to the section titled Object lifetime management.