setTimeout(() => { //定时器 ???console.log("3 seconds have passed");}, 3000);setInterval(function () { //延时循环 ???console.log("2 seconds have passed")}, 2000);timer = setInterval(() => { ???console.log("2 seconds have passed")}, 2000)cleatInterval(timer)console.log(__dirname);console.log(__filename);//回调函数function ?callFunction(fun, name) { ???fun(name);}callFunction(function(name) { ???console.log(name + ‘Bye‘);}, ‘rails365‘);//模块//1----------//count.jsvar counter = function(arr) { ???return "There are " + arr.length + " elements in the array";}module.exports = counter;//app.jsvar counter = require(‘./count‘);console.log(counter([‘ruby‘, ‘nodejs‘, ‘react‘]));//2-------------//count.jsvar counter = function (arr) { ???return "There are " + arr.length + " elements in the array";}var adder = function (a, b) { ???return `the sum of the 2 numbers is ${a + b}`;}var pi = 3.14module.exports.counter = counter;module.exports.adder = adder;module.exports.pi = pi;//另一种写法module.exports = { ???counter: counter, ???adder: adder, ???pi: pi}//app.jsvar stuff = require(‘./count‘);console.log(stuff.counter([‘ruby‘, ‘nodejs‘, ‘react‘]));console.log(stuff.adder(3.2));console.log(stuff.pi);//end 模块------------//事件var events = require(‘events‘);//引入事件模块var myEmitter = new events.EventEmitter();//创建事件对象myEmitter.on(‘someEvent‘, function (message) {//事件对象监听‘someEvent‘事件 ???console.log(message);})//手动触发‘someEvent‘事件，传递参数‘the event was emitted‘myEmitter.emit(‘someEvent‘, ‘the event was emitted‘);//============var events = require(‘events‘);var util = require(‘util‘);var Person = function (name) { ???this.name = name}//令Person继承events.EventEmitter, 使Person有事件触发util.inherits(Person, events.EventEmitter);var xiaoming = new Person(‘xiaoming‘);var lili = new Person(‘lili‘);var lucy = new Person(‘lucy‘);var person = [xiaoming, lili, lucy];person.forEach(function(person) { ???person.on(‘speak‘, function(message) { ???????console.log(person.name + " said:" + message); ???})})//end 事件--------//读写文件（同步，异步）-----var fs = require(‘fs‘);//Sync同步，会阻塞，等待语句执行完成才往下执行var readMe = fs.readFileSync("readMe.txt", "utf8");console.log(readMe);fs.writeFileSync("writeMe.txt", "write sting");console.log("finished")//2异步-----var fs = require(‘fs‘);//异步，线程遇到IO不阻塞，不进行IO操作，而是将其放入事件队列，且开辟了一个子线程处理事件队列中的事件，//主线程继续向下执行语句，子线程对事件处理完毕了会通知主线程var readMe = fs.readFile("readMe.txt", "utf8", function(err, data){ ???console.log(data)});console.log("finished")nodejs
原文地址：https://www.cnblogs.com/ravener/p/9892597.html