Copy/pastable files from https://medium.com/jspoint/a-simple-guide-to-load-c-c-code-into-node-js-javascript-applications-3fcccf54fd32

index.cpp

#include <napi.h>
#include <string>
#include "greeting.h"

// native C++ function that is assigned to `greetHello` property on `exports` object
Napi::String greetHello(const Napi::CallbackInfo& info) {
  Napi::Env env = info.Env();
  
  // call `helloUser` function from `greeting.cpp` file
  // WARNING: We are passing hardcoded `MIKE` value for now
  std::string result = helloUser( "MIKE" );

  // return new `Napi::String` value
  return Napi::String::New(env, result);
}

// callback method when module is registered with Node.js
Napi::Object Init(Napi::Env env, Napi::Object exports) {

  // set a key on `exports` object
  exports.Set(
    Napi::String::New(env, "greetHello"), // property name => "greetHello"
    Napi::Function::New(env, greetHello) // property value => `greetHello` function
  );

  // return `exports` object (always)
  return exports;
}

// register `greet` module which calls `Init` method
NODE_API_MODULE(greet, Init)

index.js

const greetModule = require( './build/Release/greet.node' );

// see properties on `exports` object
console.log( 'exports : ', greetModule );
console.log();

// execute `greetHello` function
console.log( 'greetModule.greetHello() : ', greetModule.greetHello() );
console.log();