使用node.js从C ++调用JavaScript [英] Calling JavaScript from C++ with node.js

问题描述

是否可以通过node.js从C ++调用JS函数（作为回调或类似方法）？
如果是，如何？
我正在网上搜索它，但没有找到任何有用的资源。

Is there a way to call JS functions from C++ through node.js (as callbacks or something like that)? If yes, how? I'm searching for it on the web, but haven't found any helpful resource.

预先感谢

推荐答案

形成本机插件的一种方法是使用提供的函数作为回调，例如，让我们假设您有一个名为<$ c $的函数。在您的本机环境（本机附加组件）中声明的c> setPrintFunction（）：

One way to do it form a native addon can be using the provided function as a callback, for example let's gonna assume that you have a function named setPrintFunction() declared in your native environment (A native addon):

（例如，调用 main .cc ）

#include <node.h>
#include <string>

v8::Persistent<v8::Function> fn;

// Call this at any time, but after the capture!
void printToNode(std::string msg) {
  auto isolate = fn->GetIsolate();
  // This part is the one that transforms your std::string to a javascript
  // string, and passes it as the first argument:
  const unsigned argc = 1;
  auto argv[argc] = {
      v8::String::NewFromUtf8(isolate,
                          msg.c_str(),
                          v8::NewStringType::kNormal).ToLocalChecked()
  };
  cb->Call(context, Null(isolate), argc, argv).ToLocalChecked();
}

// This is your native function that captures the reference
void setPrintFunction(const v8::FunctionCallbackInfo<Value>& args) {
  auto isolate = args.GetIsolate();
  auto context = isolate->GetCurrentContext();
  auto cb = v8::Local<v8::Function>::Cast(args[0]);
  fn = v8::Persistent<v8::Function>::New(cb);
}

// This part exports the function
void Init(v8::Local<v8::Object> exports, v8::Local<v8::Object> module) {
  NODE_SET_METHOD(module, "exports", setPrintFunction);
}

NODE_MODULE(NODE_GYP_MODULE_NAME, Init)

然后，只需导入您的插件并使用它即可：

Then, just importing your addon and using it like:

（例如，以 index.js 为例）

const { setPrintFunction } = require('<your path to .node file>');

function printNodeMsg(msg) {
  console.log('<msg>: ' + msg);
}

setPrintFunction(printNodeMsg);

因此，您基本上要做的是捕获对 v8的引用： ：Function （这是javascript函数，但在本机环境中），然后调用它并传递 Hello World！ 作为第一个（和唯一）参数。

So what you're basically doing is capturing the reference to the v8::Function (Which is the javascript function, but in the native environment) and then invoking it and passing "Hello World!" as the first (and unique) parameter.

有关此主题的更多信息： https://nodejs.org/api/addons.html

More on the subject: https://nodejs.org/api/addons.html

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