require.main
- 
类型:<module> | <undefined> ¥Type: <module> | <undefined> 
Module 对象代表 Node.js 进程启动时加载的入口脚本,如果程序的入口点不是 CommonJS 模块,则为 undefined。参见 "访问主模块"。
¥The Module object representing the entry script loaded when the Node.js
process launched, or undefined if the entry point of the program is not a
CommonJS module.
See "Accessing the main module".
在 entry.js 脚本中:
¥In entry.js script:
console.log(require.main); node entry.js Module {
  id: '.',
  path: '/absolute/path/to',
  exports: {},
  filename: '/absolute/path/to/entry.js',
  loaded: false,
  children: [],
  paths:
   [ '/absolute/path/to/node_modules',
     '/absolute/path/node_modules',
     '/absolute/node_modules',
     '/node_modules' ] }