使用 JavaScript 函数

¥Working with JavaScript functions

Node-API 提供了一组 API，允许 JavaScript 代码回调原生代码。支持回调原生代码的 Node-API 接受由 napi_callback 类型表示的回调函数。当 JavaScript VM 回调原生代码时，将调用提供的 napi_callback 函数。本节中记录的 API 允许回调函数执行以下操作：

¥Node-API provides a set of APIs that allow JavaScript code to call back into native code. Node-APIs that support calling back into native code take in a callback functions represented by the napi_callback type. When the JavaScript VM calls back to native code, the napi_callback function provided is invoked. The APIs documented in this section allow the callback function to do the following:

• 获取有关调用回调的上下文的信息。

  ¥Get information about the context in which the callback was invoked.

• 获取传递给回调的参数。

  ¥Get the arguments passed into the callback.

• 从回调中返回 napi_value。

  ¥Return a napi_value back from the callback.

此外，Node-API 提供了一组函数，允许从原生代码调用 JavaScript 函数。可以像常规 JavaScript 函数调用一样调用函数，也可以作为构造函数调用。

¥Additionally, Node-API provides a set of functions which allow calling JavaScript functions from native code. One can either call a function like a regular JavaScript function call, or as a constructor function.

通过 napi_property_descriptor 项的 data 字段传递给此 API 的任何非 NULL 数据都可以与 object 相关联，并在 object 通过将 object 和数据传递给 napi_add_finalizer 进行垃圾回收时释放。

¥Any non-NULL data which is passed to this API via the data field of the napi_property_descriptor items can be associated with object and freed whenever object is garbage-collected by passing both object and the data to napi_add_finalizer.