c 怎么调用js方法调用

#include <v8.h>

int main(int argc, char* argv[]) {
    // Initialize V8.
    v8::V8::InitializeICUDefaultLocation(argv[0]);
    v8::V8::InitializeExternalStartupData(argv[0]);
    std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
    v8::V8::InitializePlatform(platform.get());
    v8::V8::Initialize();

    // Create a new Isolate and make it the current one.
    v8::Isolate::CreateParams create_params;
    create_params.array_buffer_allocator =
        v8::ArrayBuffer::Allocator::NewDefaultAllocator();
    v8::Isolate* isolate = v8::Isolate::New(create_params);
    {
        v8::Isolate::Scope isolate_scope(isolate);
        v8::HandleScope handle_scope(isolate);
        v8::Local<v8::Context> context = v8::Context::New(isolate);
        v8::Context::Scope context_scope(context);

        // Define a JavaScript function.
        const char* js_source =
            "function add(a, b) { return a + b; }"
            "add(2, 3);";

        // Compile and run the JavaScript source.
        v8::Local<v8::String> source =
            v8::String::NewFromUtf8(isolate, js_source,
                                    v8::NewStringType::kNormal).ToLocalChecked();
        v8::Local<v8::Script> script =
            v8::Script::Compile(context, source).ToLocalChecked();
        v8::Local<v8::Value> result = script->Run(context).ToLocalChecked();

        // Convert the result to an int and print it.
        int32_t int_result = result->Int32Value(context).FromJust();
        printf("Result of add function: %d\n", int_result);
    }

    // Dispose the isolate and tear down V8.
    isolate->Dispose();
    v8::V8::Dispose();
    v8::V8::ShutdownPlatform();
    delete create_params.array_buffer_allocator;

    return 0;
}

#include <node.h>

using namespace v8;

void Add(const FunctionCallbackInfo<Value>& args) {
    Isolate* isolate = args.GetIsolate();
    double value = args[0]->NumberValue() + args[1]->NumberValue();
    Local<Number> num = Number::New(isolate, value);
    args.GetReturnValue().Set(num);
}

void Initialize(Local<Object> exports) {
    NODE_SET_METHOD(exports, "add", Add);
}

NODE_MODULE(addon, Initialize)

const addon = require('./build/Release/addon');
console.log(addon.add(2, 3)); // Outputs: 5

#include <emscripten.h>

EMSCRIPTEN_KEEPALIVE
int add(int a, int b) {
    return a + b;
}

fetch('add.wasm')
    .then(response => response.arrayBuffer())
    .then(bytes => WebAssembly.instantiate(bytes))
    .then(results => {
        const instance = results.instance;
        console.log(instance.exports.add(2, 3)); // Outputs: 5
    });