构建

编写源代码后，必须将其编译为二进制 addon.node 文件。 为此，请在项目的顶层创建名为 binding.gyp 的文件，使用类似 JSON 的格式描述模块的构建配置。 该文件由 node-gyp 使用，这是一个专门为编译 Node.js 插件而编写的工具。

Once the source code has been written, it must be compiled into the binary addon.node file. To do so, create a file called binding.gyp in the top-level of the project describing the build configuration of the module using a JSON-like format. This file is used by node-gyp, a tool written specifically to compile Node.js addons.

{
  "targets": [
    {
      "target_name": "addon",
      "sources": [ "hello.cc" ]
    }
  ]
}

A version of the node-gyp utility is bundled and distributed with Node.js as part of npm. This version is not made directly available for developers to use and is intended only to support the ability to use the npm install command to compile and install addons. Developers who wish to use node-gyp directly can install it using the command npm install -g node-gyp. See the node-gyp installation instructions for more information, including platform-specific requirements.

Once the binding.gyp file has been created, use node-gyp configure to generate the appropriate project build files for the current platform. This will generate either a Makefile (on Unix platforms) or a vcxproj file (on Windows) in the build/ directory.

Next, invoke the node-gyp build command to generate the compiled addon.node file. This will be put into the build/Release/ directory.

When using npm install to install a Node.js addon, npm uses its own bundled version of node-gyp to perform this same set of actions, generating a compiled version of the addon for the user's platform on demand.

Once built, the binary addon can be used from within Node.js by pointing require() to the built addon.node module:

// hello.js
const addon = require('./build/Release/addon');

console.log(addon.hello());
// Prints: 'world'

Because the exact path to the compiled addon binary can vary depending on how it is compiled (i.e. sometimes it may be in ./build/Debug/), addons can use the bindings package to load the compiled module.

While the bindings package implementation is more sophisticated in how it locates addon modules, it is essentially using a try…catch pattern similar to:

try {
  return require('./build/Release/addon.node');
} catch (err) {
  return require('./build/Debug/addon.node');
}