global

//node中的全局变量是global, 浏览器中的全局变量是window
> global.console
Console {
  log: [Function: bound consoleCall],
  info: [Function: bound consoleCall],
  warn: [Function: bound consoleCall],
  error: [Function: bound consoleCall],
  dir: [Function: bound consoleCall],
  time: [Function: bound consoleCall],
  timeEnd: [Function: bound consoleCall],
  trace: [Function: bound consoleCall],
  assert: [Function: bound consoleCall],
  clear: [Function: bound consoleCall],
  count: [Function: bound consoleCall],
  countReset: [Function: bound countReset],
  Console: [Function: Console],
  debug: [Function: debug],
  dirxml: [Function: dirxml],
  table: [Function: table],
  group: [Function: group],
  groupCollapsed: [Function: groupCollapsed],
  groupEnd: [Function: groupEnd],
  markTimeline: [Function: markTimeline],
  profile: [Function: profile],
  profileEnd: [Function: profileEnd],
  timeline: [Function: timeline],
  timelineEnd: [Function: timelineEnd],
  timeStamp: [Function: timeStamp],
  [Symbol(counts)]: Map {} }

process

> process === global.process;
true
> process.version;
'v8.4.0'
> process.platform;
'darwin'
> process.arch;
'x64'
> process.cwd(); //返回当前工作目录
'/Users/michael'
> process.chdir('/private/tmp'); // 切换当前工作目录
undefined
> process.cwd();
'/private/tmp'

//在下一次事件响应中执行代码，可以调用process.nextTick()
process.nextTick(function () {
    console.log('nextTick callback!');
});
console.log('nextTick was set!');

//程序即将退出时的回调函数:
process.on('exit', function (code) {
    console.log('about to exit with code: ' + code);
});

//判断js的执行环境
if (typeof(window) === 'undefined') {
    console.log('node.js');
} else {
    console.log('browser');
}

fs

//fs是指文件系统模块，一般包括同步和异步处理文件，node.js中一般是通过异步处理文件
'use strict';

var fs = require('fs'); //引入模块

fs.readFile('./demo.js', 'utf-8', function (err, data) {
    if (err) {
        console.log(err);
    } else {
        console.log(data);
    }
});

stream

stream是Node.js提供的又一个仅在服务区端可用的模块，目的是支持“流”这种数据结构

http

用程序并不直接和HTTP协议打交道，而是操作http模块提供的request和response对象

crypto

crypto模块的目的是为了提供通用的加密和哈希算法