node笔记一之全局对象

node全局对象相关

1. 全局对象相关

// 1.全局对象global，和浏览器中的window相似
console.log(global);
========>>打印结果
Object [global] {
  global: [Circular *1],
  queueMicrotask: [Function: queueMicrotask],
  clearImmediate: [Function: clearImmediate],
  setImmediate: [Function: setImmediate] {
    [Symbol(nodejs.util.promisify.custom)]: [Getter]
  },
  structuredClone: [Function: structuredClone],
  clearInterval: [Function: clearInterval],
  clearTimeout: [Function: clearTimeout],
  setInterval: [Function: setInterval],
  setTimeout: [Function: setTimeout] {
    [Symbol(nodejs.util.promisify.custom)]: [Getter]
  },
  atob: [Function: atob],
  btoa: [Function: btoa],
  performance: Performance {
    nodeTiming: PerformanceNodeTiming {
      name: 'node',
      entryType: 'node',
      startTime: 0,
      duration: 34.0697078704834,
      nodeStart: 2.216874837875366,
      v8Start: 6.030207872390747,
      bootstrapComplete: 28.79891586303711,
      environment: 17.475457906723022,
      loopStart: -1,
      loopExit: -1,
      idleTime: 0
    },
    timeOrigin: 1684209790544.549
  },
  fetch: [AsyncFunction: fetch]
}

2.全局对象，引用自己

和【window === window.window】一样 console.log(global === global.global) ==》 ture;

3.timer是个对象， 在浏览器环境是数子ID

const timer = setTimeout(() => { console.log(1); }, 1000); console.log(timer);

4.类似于 setTimeout(fn，0)

const timer = setImmediate(() => { console.log(1); });
console.log(timer); // 输出对象
========>>打印结果
Timeout {
  _idleTimeout: 1000,
  _idlePrev: [TimersList],
  _idleNext: [TimersList],
  _idleStart: 15,
  _onTimeout: [Function (anonymous)],
  _timerArgs: undefined,
  _repeat: null,
  _destroyed: false,
  [Symbol(refed)]: true,
  [Symbol(kHasPrimitive)]: false,
  [Symbol(asyncId)]: 2,
  [Symbol(triggerId)]: 1
}

5.console， 没啥好说的

6.__dirname 获取当前模块所在的目录 【并非global的属性】

console.log(__dirname); 
// /Users/fuxing/Desktop/project/code/web/node/node_xuexi 

console.log(global.__dirname);// undefined

7.__filename 获取当前模块文件的路径 【并非global的属性】

console.log(__filename); 
// /Users/fuxing/Desktop/project/code/web/node/node_xuexi/demo001.js

8.Buffer 类型化数组 继承自 UIntArray

9. process 进程

9.1 process.cwd() 返回当前nodejs进程的工作目录 绝对路径

console.log("当前命令行： ", process.cwd()); 
// /Users/fuxing/Desktop/project/code/web/node

9.2 process.exit() 强制退出当前的node进程 。可传入退出码，0标识成功退出，默认0

setTimeout(() => { console.log("abc"); }, 1000);
process.exit(0);

9.3 process.argv 【string[] 获取命令中的所有参数】

console.log(process.argv);

终端运行： node demo001 1 2 3 a b c
输出
[
    '/usr/local/bin/node',
    '/Users/fuxing/Desktop/project/code/web/node/node_xuexi/demo001',
    '1',
    '2',
    '3',
    'a',
    'b',
    'c'
  ]

9.4 process.platform 获取当前的操作系统

console.log(process.platform); 
// darwin/win32 Mac的操作系统

9.5 process.kill() 根据进程ID杀死进程

process.kill(5786);

9.6 process.env 获取环境变量 --- 很有用的

console.log(process.env);
========>>打印结果
{
    MANPATH: '/Users/fuxing/.nvm/versions/node/v18.13.0/share/man:/opt/homebrew/share/man::',
    VSCODE_CRASH_REPORTER_PROCESS_TYPE: 'extensionHost',
    NVM_CD_FLAGS: '-q',
    SHELL: '/bin/zsh',
    HOMEBREW_BOTTLE_DOMAIN: 'https://mirrors.ustc.edu.cn/homebrew-bottles/bottles',
    TMPDIR: '/var/folders/dn/c54d7cqd2gscfn61khs9mdfm0000gn/T/',
    HOMEBREW_REPOSITORY: '/opt/homebrew',
    ORIGINAL_XDG_CURRENT_DESKTOP: 'undefined',
    MallocNanoZone: '0',
    USER: 'fuxing',
    NVM_DIR: '/Users/fuxing/.nvm',
    COMMAND_MODE: 'unix2003',
    SSH_AUTH_SOCK: '/private/tmp/com.apple.launchd.idNkN5Z5Mh/Listeners',
    __CF_USER_TEXT_ENCODING: '0x1F5:0x19:0x34',
    ELECTRON_RUN_AS_NODE: '1',
    VSCODE_AMD_ENTRYPOINT: 'vs/workbench/api/node/extensionHostProcess',
    PATH: '/Users/fuxing/.nvm/versions/node/v18.13.0/bin:/Library/Frameworks/Python.framework/Versions/3.11/bin:/opt/homebrew/bin:/opt/homebrew/sbin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin',
    _: '/Users/fuxing/.nvm/versions/node/v18.13.0/bin/node',
    __CFBundleIdentifier: 'com.microsoft.VSCode',
    PWD: '/Users/fuxing/Desktop/project/code/web/node',
    VSCODE_HANDLES_UNCAUGHT_ERRORS: 'true',
    XPC_FLAGS: '0x0',
    XPC_SERVICE_NAME: 'application.com.microsoft.VSCode.42889349.42889355',
    SHLVL: '1',
    HOME: '/Users/fuxing',
    VSCODE_NLS_CONFIG: '{"locale":"zh-cn","osLocale":"zh-cn","availableLanguages":{"*":"zh-cn"},"_languagePackId":"07d862891cffead1799ff1d0d31a0385.zh-cn","_translationsConfigFile":"/Users/fuxing/Library/Application Support/Code/clp/07d862891cffead1799ff1d0d31a0385.zh-cn/tcf.json","_cacheRoot":"/Users/fuxing/Library/Application Support/Code/clp/07d862891cffead1799ff1d0d31a0385.zh-cn","_resolvedLanguagePackCoreLocation":"/Users/fuxing/Library/Application Support/Code/clp/07d862891cffead1799ff1d0d31a0385.zh-cn/6a995c4f4cc2ced6e3237749973982e751cb0bf9","_corruptedFile":"/Users/fuxing/Library/Application Support/Code/clp/07d862891cffead1799ff1d0d31a0385.zh-cn/corrupted.info","_languagePackSupport":true}',
    HOMEBREW_PREFIX: '/opt/homebrew',
    LOGNAME: 'fuxing',
    VSCODE_IPC_HOOK: '/Users/fuxing/Library/Application Support/Code/1.78-main.sock',
    VSCODE_CODE_CACHE_PATH: '/Users/fuxing/Library/Application Support/Code/CachedData/6a995c4f4cc2ced6e3237749973982e751cb0bf9',
    NVM_BIN: '/Users/fuxing/.nvm/versions/node/v18.13.0/bin',
    VSCODE_PID: '79115',
    INFOPATH: '/opt/homebrew/share/info:',
    HOMEBREW_CELLAR: '/opt/homebrew/Cellar',
    VSCODE_CWD: '/'
  }