构建

当源代码已被编写，它必须被编译成二进制 addon.node 文件。 要做到这点，需在项目的顶层创建一个名为 binding.gyp 的文件，它使用一个类似 JSON 的格式来描述模块的构建配置。 该文件会被 node-gyp（一个用于编译 Node.js 插件的工具）使用。

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

Node.js 会捆绑与发布一个版本的 node-gyp 工具作为 npm 的一部分。 该版本不可以直接被开发者使用，仅为了支持使用 npm install 命令编译与安装插件的能力。 需要直接使用 node-gyp 的开发者可以使用 npm install -g node-gyp 命令进行安装。 查看 node-gyp 安装说明了解更多信息，包括平台特定的要求。

但 binding.gyp 文件已被创建，使用 node-gyp configure 为当前平台生成相应的项目构建文件。 这会在 build/ 目录下生成一个 Makefile 文件（在 Unix 平台上）或 vcxproj 文件（在 Windows 上）。

下一步，调用 node-gyp build 命令生成编译后的 addon.node 的文件。 它会被放进 build/Release/ 目录。

当使用 npm install 安装一个 Node.js 插件时，npm 会使用自身捆绑的 node-gyp 版本来执行同样的一套动作，为用户要求的平台生成一个插件编译后的版本。

当构建完成时，二进制插件就可以在 Node.js 中被使用，通过 require() 构建后的 addon.node 模块：

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

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

因为编译后的二进制插件的确切路径取决于它如何被编译（比如有时它可能在 ./build/Debug/ 中），所以插件可以使用 bindings 包加载编译后的模块。

虽然 bindings 包在如何定位插件模块的实现上更复杂，但它本质上使用了一个 try…catch 模式，类似如下：

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

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');
}