node.js calls module example developed in C_node.js

How to use C to interact with node. In the node program, if there is a large amount of data calculation, which is relatively slow to process, you can use C to process it, and then return it to the node through a callback (in the form of a callback). Let’s first review the orthodox method of developing native modules in C

#include <node.h> 
#include <v8.h> 
using namespace v8; 
 
// 这里是 hello 函数的 C++ 实现部分 
Handle<Value> Method(const Arguments& args) { 
 HandleScope scope; 
 return scope.Close(String::New("world")); 
} 
 
// 这里是模块的初始化函数，必须有 
void init(Handle<Object> exports) { 
 exports->Set(String::NewSymbol("hello"), 
   FunctionTemplate::New(Method)->GetFunction()); 
} 
 
// 这里定义本模块的名字和初始化函数 
NODE_MODULE(hello, init)

If this module is written in Node, it looks like this:

exports.hello = function() { 
 return 'world'; 
};


为了编译 C++ 这个模块，还需要一个 JSON 格式的 binding.gyp 文件，来定义编译的细节。 
{ 
 "targets": [ 
  { 
   "target_name": "hello", 
   "sources": [ "hello.cpp" ] 
  } 
 ] 
}

Execute node-gyp configure build to compile directly.

node test.js: 
var addon = require('./build/Release/hello'); 

console.log(addon.hello()); 

Output the result.

In this way, node can directly call programs written in C.

Explanation of the above program: In hello.cc, we first created a function Method, which returns a string of "hello, world", and then we created an init function as an initialization function , we called a function

Finally, we bind this module as: NODE_MODULE(hello, init)

It is pointed out on the official website that all node plug-ins must output an initialization function, which means that the following code must be in each module and has a fixed format.

void Initialize (Handle<Object> exports); 
NODE_MODULE(module_name, Initialize) 

The module_name must correspond to the target_name in binding.gyp.

After node-gyp configure build is compiled, a new build folder will be generated under the current file. By referencing the result of this build in test.js, we can call the program written in C.