napi_make_callback

NAPI_EXTERN napi_status napi_make_callback(napi_env env,
                                           napi_async_context async_context,
                                           napi_value recv,
                                           napi_value func,
                                           size_t argc,
                                           const napi_value* argv,
                                           napi_value* result); 拷贝

• [in] env：调用 API 的环境。

  ¥[in] env: The environment that the API is invoked under.

• [in] async_context：调用回调的异步操作的上下文。这通常应该是以前从 napi_async_init 获得的值。为了保持与以前版本的 ABI 兼容性，为 async_context 传递 NULL 不会导致错误。但是，这会导致异步钩子的错误操作。潜在问题包括使用 AsyncLocalStorage API 时丢失异步上下文。

  ¥[in] async_context: Context for the async operation that is invoking the callback. This should normally be a value previously obtained from napi_async_init. In order to retain ABI compatibility with previous versions, passing NULL for async_context does not result in an error. However, this results in incorrect operation of async hooks. Potential issues include loss of async context when using the AsyncLocalStorage API.

• [in] recv：传递给被调用函数的 this 值。

  ¥[in] recv: The this value passed to the called function.

• [in] func：napi_value 表示要调用的 JavaScript 函数。

  ¥[in] func: napi_value representing the JavaScript function to be invoked.

• [in] argc：argv 数组中的元素数。

  ¥[in] argc: The count of elements in the argv array.

• [in] argv：JavaScript 值数组 napi_value 表示函数的参数。如果 argc 为零，则可以通过传入 NULL 来省略此参数。

  ¥[in] argv: Array of JavaScript values as napi_value representing the arguments to the function. If argc is zero this parameter may be omitted by passing in NULL.

• [out] result：napi_value 表示返回的 JavaScript 对象。

  ¥[out] result: napi_value representing the JavaScript object returned.

如果 API 成功，则返回 napi_ok。

¥Returns napi_ok if the API succeeded.

此方法允许从原生附加组件调用 JavaScript 函数对象。这个 API 类似于 napi_call_function。但是，它用于在从异步操作返回后（当堆栈上没有其他脚本时）从原生代码调用回 JavaScript。它是 node::MakeCallback 的一个相当简单的封装器。

¥This method allows a JavaScript function object to be called from a native add-on. This API is similar to napi_call_function. However, it is used to call from native code back into JavaScript after returning from an async operation (when there is no other script on the stack). It is a fairly simple wrapper around node::MakeCallback.

请注意，不必在 napi_async_complete_callback 中使用 napi_make_callback；在这种情况下，回调的异步上下文已经设置好，因此直接调用 napi_call_function 就足够且合适了。实现不使用 napi_create_async_work 的自定义异步行为时，可能需要使用 napi_make_callback 函数。

¥Note it is not necessary to use napi_make_callback from within a napi_async_complete_callback; in that situation the callback's async context has already been set up, so a direct call to napi_call_function is sufficient and appropriate. Use of the napi_make_callback function may be required when implementing custom async behavior that does not use napi_create_async_work.

在回调期间由 JavaScript 在微任务队列上安排的任何 process.nextTick 或 Promises 在返回到 C/C++ 之前运行。

¥Any process.nextTicks or Promises scheduled on the microtask queue by JavaScript during the callback are ran before returning back to C/C++.