是什么

在浏览器中全局对象是window, 而在nodejs环境中是global

nodejs中变量都是当前模块的，外面变量可以通过require引用，exports暴露

有哪些

全局对象分成两类：

• 真正的全局变量
• 模块级别的全局变量

全局级别

• global
• process
• console
• setTimeout/setInterval/clearTimeout/clearInterval
• Buffer

模块级别

• exports
• require
• module
• __dirname
• __filename

怎么用

• global

  console.log(process === global.process)

• process

node code/fe-engin/node/process.js fang 10 down
// index.js
process.argv.forEach((val, index) => {
  console.log(`${index}: ${val}`);
});

输出结果

0: /usr/local/bin/node
1: /Users/code/fe-engin/node/process.js
2: fang
3: 10
4: down

Type ".help" for more information.
> process
process {
  version: 'v12.16.3',
  versions: {
    node: '12.16.3',
    v8: '7.8.279.23-node.35',
    uv: '1.34.2',
    zlib: '1.2.11',
    brotli: '1.0.7',
    ares: '1.16.0',
    modules: '72',
    nghttp2: '1.40.0',
    napi: '5',
    llhttp: '2.0.4',
    http_parser: '2.9.3',
    openssl: '1.1.1g',
    cldr: '36.0',
    icu: '65.1',
    tz: '2019c',
    unicode: '12.1'
  },
  arch: 'x64',
  platform: 'darwin',
  release: {
    name: 'node',
    lts: 'Erbium',
    sourceUrl: 'https://nodejs.org/download/release/v12.16.3/node-v12.16.3.tar.gz',
    headersUrl: 'https://nodejs.org/download/release/v12.16.3/node-v12.16.3-headers.tar.gz'

• console 和浏览器无异
• setTimeout/setInterval/clearTimeout/clearInterval 定时器类
• Buffer

可以处理二进制以及非Unicode编码的数据

• exports

console.log(exports) // {}

• require

[Function: require] {
  resolve: [Function: resolve] { paths: [Function: paths] },
  main: Module {
    id: '.',
    path: '/Users/###/code/fe-engin/node',
    exports: {},
    parent: null,
    filename: '/Users/###/code/fe-engin/node/exports.js',
    loaded: false,
    children: [],
    paths: [
      '/Users/###/code/fe-engin/node/node_modules',
      '/Users/###/code/fe-engin/node_modules',
      '/Users/###/code/node_modules',
      '/Users/###/node_modules',
      '/Users/###/Desktop/fangdown/github/node_modules',
      '/Users/###/Desktop/fangdown/node_modules',
      '/Users/###/Desktop/node_modules',
      '/Users/###/node_modules',
      '/Users/node_modules',
      '/node_modules'
    ]
  },
  extensions: [Object: null prototype] {
    '.js': [Function],
    '.json': [Function],
    '.node': [Function]
  },
  cache: [Object: null prototype] {
    '/Users/###/code/fe-engin/node/exports.js': Module {
      id: '.',
      path: '/Users/###/code/fe-engin/node',
      exports: {},
      parent: null,
      filename: '/Users/###/code/fe-engin/node/exports.js',
      loaded: false,
      children: [],
      paths: [Array]
    }
  }
}

• module

Module {
  id: '.',
  path: '/Users/###/code/fe-engin/node',
  exports: {},
  parent: null,
  filename: '/Users/###/code/fe-engin/node/exports.js',
  loaded: false,
  children: [],
  paths: [
    '/Users/###/code/fe-engin/node/node_modules',
    '/Users/###/code/fe-engin/node_modules',
    '/Users/###/code/node_modules',
    '/Users/###/node_modules',
    '/Users/###/Desktop/fangdown/github/node_modules',
    '/Users/###/Desktop/fangdown/node_modules',
    '/Users/###/Desktop/node_modules',
    '/Users/###/node_modules',
    '/Users/node_modules',
    '/node_modules'
  ]
}

• __dirname

/Users/###/Desktop/fangdown/github/app-blog/code/fe-engin/node

• __filename

/Users/###/Desktop/fangdown/github/app-blog/code/fe-engin/node/exports.js

FAQ