C Addons no Node.js

What are C Addons?

They are a way to increase the performance and functionality of your Node.js code, extending C code directly in the JavaScript environment. In other words, a C addon is a module you create for Node.js that allows you to write C functions and libraries and use them in your JavaScript code.

They are basically a bridge between JavaScript and C, which means that Node.js can run heavier codes without losing flexibility and, above all, its simplicity.

Reasons to use C Addons in Node.js

• Perfomance: C is a compiled language, it generally presents superior performance when compared to JavaScript, which is an interpreted language. In addition to allowing more controlled use of memory allocation and deallocation.
• Libraries and legacy code: Many legacy systems and libraries were developed in C . Addons allow you to efficiently integrate these libraries into your environment, facilitating the reuse of existing code bases and reducing rewriting effort. In addition to having access to a range of libraries that do not work directly in JavaScript
• System level: Certain system-level features, which are not accessible by JavaScript, can be used with the help of addons, allowing the use of specific functionalities whenever necessary.

How do C Addons work?

• Compilation: An addon needs to be compiled before it can be used. To do this, you need to have node-gyp configured in your repository. This tool compiles C code into a "native" module that Node.js can run.
• Bindings: To create a "bridge" between JavaScript and C, you can use the N-API, NAN packages and/or directly through V8, libuv, and alternative Node.js libraries .
• Loading the features: Once the code is compiled and a "bridge" exists between the two worlds, the created functions can be called through require(), causing them to be accessible to JavaScript

Practical Example

First, let's create a directory for our code

 mkdir addon
 cd addon

Next, let's create initialize our package.json and download the lib node-gyp (make sure to correctly install the dependencies on your OS)

npm init -y
npm i node-gyp

Within our package.json, we will create a build script for our addon.

 mkdir addon
 cd addon

Now, we will create our addon in C and configure our binding.

npm init -y
npm i node-gyp

 "scripts": {
    "build": "node-gyp configure build"
  }

Ready, once these two files are created, we can run our build script (npm run build) and wait for the entire process to be able to enjoy our addon. Next, we will create a new file and execute the command node index.js
in the terminal

// array_sum.cpp
#include <node.h>
namespace demo
{

  using v8::Array;
  using v8::Context;
  using v8::Exception;
  using v8::FunctionCallbackInfo;
  using v8::Isolate;
  using v8::Local;
  using v8::Number;
  using v8::Object;
  using v8::Value;

  void SumArray(const FunctionCallbackInfo<Value> &args)
  {
    Isolate *isolate = args.GetIsolate();
    Local<Context> context = isolate->GetCurrentContext();

    Local<Array> array = Local<Array>::Cast(args[0]);
    uint32_t length = array->Length();
    double sum = 0;

    for (uint32_t i = 0; i < length; ++i)
    {
      Local<Value> element = array->Get(context, i).ToLocalChecked();
      if (element->IsNumber())
      {
        sum += element->NumberValue(context).FromJust();
      }
    }

    args.GetReturnValue().Set(Number::New(isolate, sum));
  }

  void Initialize(Local<Object> exports)
  {
    NODE_SET_METHOD(exports, "sum", SumArray);
  }

  NODE_MODULE(NODE_GYP_MODULE_NAME, Initialize)
}

Final considerations

Addons are powerful resources when the objective is to optimize performance in critical operations or integrate with native code. Although they require knowledge of C and increase project complexity, they can be the perfect solution for situations where pure JavaScript does not offer the ideal solution. Thanks to tools like N-API, addon development has become more accessible and stable, allowing your projects to combine the practicality of JavaScript with the efficiency of C .

Repository Link: cpp-addon-nodejs
References: Node.js

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