98 lines
2.5 KiB
Markdown
98 lines
2.5 KiB
Markdown
# CallbackInfo
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The object representing the components of the JavaScript request being made.
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The `Napi::CallbackInfo` object is usually created and passed by the Node.js runtime or node-addon-api infrastructure.
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The `Napi::CallbackInfo` object contains the arguments passed by the caller. The number of arguments is returned by the `Length` method. Each individual argument can be accessed using the `operator[]` method.
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The `SetData` and `Data` methods are used to set and retrieve the data pointer contained in the `Napi::CallbackInfo` object.
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## Methods
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### Constructor
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```cpp
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Napi::CallbackInfo::CallbackInfo(napi_env env, napi_callback_info info);
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```
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- `[in] env`: The `napi_env` environment in which to construct the `Napi::CallbackInfo` object.
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- `[in] info`: The `napi_callback_info` data structure from which to construct the `Napi::CallbackInfo` object.
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### Env
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```cpp
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Napi::Env Napi::CallbackInfo::Env() const;
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```
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Returns the `Env` object in which the request is being made.
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### NewTarget
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```cpp
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Napi::Value Napi::CallbackInfo::NewTarget() const;
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```
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Returns the `new.target` value of the constructor call. If the function that was invoked (and for which the `Napi::NCallbackInfo` was passed) is not a constructor call, a call to `IsEmpty()` on the returned value returns true.
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### IsConstructCall
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```cpp
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bool Napi::CallbackInfo::IsConstructCall() const;
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```
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Returns a `bool` indicating if the function that was invoked (and for which the `Napi::CallbackInfo` was passed) is a constructor call.
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### Length
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```cpp
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size_t Napi::CallbackInfo::Length() const;
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```
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Returns the number of arguments passed in the `Napi::CallbackInfo` object.
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### operator []
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```cpp
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const Napi::Value operator [](size_t index) const;
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```
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- `[in] index`: The zero-based index of the requested argument.
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Returns a `Napi::Value` object containing the requested argument.
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### This
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```cpp
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Napi::Value Napi::CallbackInfo::This() const;
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```
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Returns the JavaScript `this` value for the call
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### Data
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```cpp
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void* Napi::CallbackInfo::Data() const;
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```
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Returns the data pointer for the callback.
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### SetData
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```cpp
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void Napi::CallbackInfo::SetData(void* data);
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```
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- `[in] data`: The new data pointer to associate with this `Napi::CallbackInfo` object.
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Returns `void`.
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### Not documented here
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```cpp
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Napi::CallbackInfo::~CallbackInfo();
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// Disallow copying to prevent multiple free of _dynamicArgs
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Napi::CallbackInfo::CallbackInfo(CallbackInfo const &) = delete;
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void Napi::CallbackInfo::operator=(CallbackInfo const &) = delete;
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```
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