Hello world


“Hello World” 示例是一个简单的插件,用 C++ 编写,相当于以下 JavaScript 代码:

module.exports.hello = () => 'world';

首先,创建 hello.cc 文件:

// hello.cc
#include <node.h>

namespace demo {

using v8::FunctionCallbackInfo;
using v8::Isolate;
using v8::Local;
using v8::Object;
using v8::String;
using v8::Value;

void Method(const FunctionCallbackInfo<Value>& args) {
  Isolate* isolate = args.GetIsolate();
  args.GetReturnValue().Set(String::NewFromUtf8(
      isolate, "world").ToLocalChecked());
}

void Initialize(Local<Object> exports) {
  NODE_SET_METHOD(exports, "hello", Method);
}

NODE_MODULE(NODE_GYP_MODULE_NAME, Initialize)

}  // 命名空间示例

注意,所有的 Node.js 插件必须导出一个如下模式的初始化函数:

void Initialize(Local<Object> exports);
NODE_MODULE(NODE_GYP_MODULE_NAME, Initialize)

NODE_MODULE 后面没有分号,因为它不是一个函数(详见 node.h)。

module_name 必须匹配最终的二进制文件名(不包括 .node 后缀)。

hello.cc 示例中,初始化函数是 Initialize,插件模块名是 addon

使用 node-gyp 构建插件时,使用宏 NODE_GYP_MODULE_NAME 作为 NODE_MODULE() 的第一个参数将确保会将最终二进制文件的名称传给 NODE_MODULE()

This "Hello world" example is a simple Addon, written in C++, that is the equivalent of the following JavaScript code:

module.exports.hello = () => 'world';

First, create the file hello.cc:

// hello.cc
#include <node.h>

namespace demo {

using v8::FunctionCallbackInfo;
using v8::Isolate;
using v8::Local;
using v8::Object;
using v8::String;
using v8::Value;

void Method(const FunctionCallbackInfo<Value>& args) {
  Isolate* isolate = args.GetIsolate();
  args.GetReturnValue().Set(String::NewFromUtf8(
      isolate, "world").ToLocalChecked());
}

void Initialize(Local<Object> exports) {
  NODE_SET_METHOD(exports, "hello", Method);
}

NODE_MODULE(NODE_GYP_MODULE_NAME, Initialize)

}  // namespace demo

All Node.js Addons must export an initialization function following the pattern:

void Initialize(Local<Object> exports);
NODE_MODULE(NODE_GYP_MODULE_NAME, Initialize)

There is no semi-colon after NODE_MODULE as it's not a function (see node.h).

The module_name must match the filename of the final binary (excluding the .node suffix).

In the hello.cc example, then, the initialization function is Initialize and the addon module name is addon.

When building addons with node-gyp, using the macro NODE_GYP_MODULE_NAME as the first parameter of NODE_MODULE() will ensure that the name of the final binary will be passed to NODE_MODULE().