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Node.js is an open source Javascript runtime for building high-performance, scalable web applications. Unlike browsers, Node.js allows Javascript to run in a server-side environment, making Javascript a more comprehensive programming language.
Node.js has many excellent features, such as asynchronous I/O operations, event-driven, etc. These features enable Node.js to efficiently handle a large number of concurrent requests. However, sometimes we need to use C or C to implement some specific functions that Node.js cannot implement, such as memory management or calling hardware-level APIs. In this case, extending Node.js with C code might be a good choice.
Node.js provides a feature called "C plug-in", which can be used to write functional extensions in C or C++. In this article, we will learn how to create a Node.js plugin using C code.
node-gyp is a tool for building Node.js plugins. To write a Node.js plugin using C code, we must first install node-gyp.
To install node-gyp, run the following command:
npm install -g node-gyp
Before extending Node.js with C code, we A C module needs to be created first. We can use node-gyp to generate a template and then modify it.
To generate a template, run the following command:
node-gyp configure
This will generate a binding.gyp file and a directory structure.
In the generated directory structure, we will find a file called "hello.cc" which contains a simple function that will return the string "world".
We can use this template to create our own modules.
Now, we can start writing our C code.
Suppose we want to create a plugin called "myaddon" in Node.js that will output the string "Hello, World!". The following is our code:
#include <node.h> using namespace v8; void Method(const FunctionCallbackInfo<Value>& args) { Isolate* isolate = args.GetIsolate(); args.GetReturnValue().Set(String::NewFromUtf8(isolate, "Hello, World!")); } void init(Local<Object> exports) { NODE_SET_METHOD(exports, "hello", Method); } NODE_MODULE(addon, init)
Here, we use the v8 namespace and Isolate class provided by Node.js to integrate our C code into Node.js.
In this simple example, we define a function called Method that accepts a FunctionCallbackInfo instance as its argument and uses that instance to return a generated string. We also use the NODE_SET_METHOD macro to attach Method functions to properties of Node.js objects. Finally, we use the NODE_MODULE macro to export our code into Node.js and give it an identifier called "addon".
Once we have written our C code, we need to use the binding.gyp file to tell node-gyp how to compile our code.
The following is a simple binding.gyp file:
{ "targets": [ { "target_name": "myaddon", "sources": [ "hello.cc" ] } ] }
Here, we define a target with the target name "myaddon" and use the hello.cc file as the source file.
Now we can use node-gyp to compile our plugin and then load it in Node.js.
First, compile our plugin using the following command:
node-gyp build
This will generate a directory called "build" in the project directory containing the files we need. Now, we can load the plugin in Node.js this way:
var addon = require('./build/Release/myaddon'); console.log(addon.hello());
This will output the string "Hello, World!" to the console.
Summary
In this article, we learned how to create a Node.js plugin using C code. By using node-gyp to build our plugin, we can easily integrate C or C code into Node.js projects, thereby extending Node.js functionality and solving some problems that Node.js cannot solve.
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