事件模型Events

1 程序1 var EventEmitter = require('events').EventEmittervar myEmitter = new EventEmitter()// addEvent

1 程序1

var EventEmitter = require('events').EventEmittervar myEmitter = new EventEmitter()// addEventListenermyEmitter.on('get', function (something) {    console.log(something + "1")})myEmitter.on('get', function (something) {    console.log(something + "2")})myEmitter.on('get', function (something) {    console.log(something + "3")})myEmitter.on('get', function (something) {    console.log(something + "4")})myEmitter.on('get', function (something) {    console.log(something + "5")})myEmitter.on('get', function (something) {    console.log(something + "6")})myEmitter.on('get', function (something) {    console.log(something + "7")})myEmitter.on('get', function (something) {    console.log(something + "8")})myEmitter.on('get', function (something) {    console.log(something + "9")})myEmitter.on('get', function (something) {    console.log(something + "10")})myEmitter.emit("get", "监听")

结果：

监听1

监听2

监听3

监听4

监听5

监听6

监听7

监听8

监听9

监听10

如果继续增加第11条监听，系统警告：Warning: Possible EventEmitter memory leak detected. 11 get listeners added. Use emitter.setMaxListeners() to increase limit，即需要setMaxListeners()方法增加监听数量。但监听数太多容易造成内存泄漏

2 程序2

var EventEmitter = require('events').EventEmittervar myEmitter = new EventEmitter()// 设置最大监听数(默认建议10个监听)myEmitter.setMaxListeners(11)// addEventListenermyEmitter.on('get', function (something) {    console.log(something + "1")})myEmitter.on('get', function (something) {    console.log(something + "2")})myEmitter.on('get', function (something) {    console.log(something + "3")})myEmitter.on('get', function (something) {    console.log(something + "4")})myEmitter.on('get', function (something) {    console.log(something + "5")})myEmitter.on('get', function (something) {    console.log(something + "6")})myEmitter.on('get', function (something) {    console.log(something + "7")})myEmitter.on('get', function (something) {    console.log(something + "8")})myEmitter.on('get', function (something) {    console.log(something + "9")})myEmitter.on('get', function (something) {    console.log(something + "10")})myEmitter.on('get', function (something) {    console.log(something + "11")})myEmitter.emit("get", "监听")

3 程序3 移除监听

var EventEmitter = require('events').EventEmittervar myEmitter = new EventEmitter()// 设置最大监听数(默认建议10个监听)myEmitter.setMaxListeners(11)// addEventListenermyEmitter.on('get', function (something) {    console.log(something + "1")})myEmitter.on('get', function (something) {    console.log(something + "2")})myEmitter.on('get', function (something) {    console.log(something + "3")})myEmitter.on('get', function (something) {    console.log(something + "4")})myEmitter.on('get', function (something) {    console.log(something + "5")})myEmitter.on('get', function (something) {    console.log(something + "6")})myEmitter.on('get', function (something) {    console.log(something + "7")})myEmitter.on('get', function (something) {    console.log(something + "8")})myEmitter.on('get', function (something) {    console.log(something + "9")})myEmitter.on('get', function (something) {    console.log(something + "10")})function getEmitter(something) {    console.log(something + "11")}myEmitter.on('get', getEmitter)// 移除监听myEmitter.removeListener('get',getEmitter)myEmitter.emit("get", "监听")

结果：移除了第11个监听

myEmitter.removeAllListeners('get')

结果：移除所有get监听事件

4 获取监听数

myEmitter.listeners('get').length// 或者EventEmitter.listenerCount(myEmitter,'get')

结果：10