NodeJS——事件监听

var EventEmitter = require('events').EventEmitter
var xx = new EventEmitter()
xx.setMaxListeners(11) //设置最大监听数量，超过的会报错（溢出），默认为10
xx.on('eventName',function)// 监听事件
xx.emit('eventName',参数)//响应监听事件，
xx.removeAllListeners() //移除xx.所有监听
xx.removeAllListeners('eventName') //移除xx.所有eventName监听
x.listeners('eventName').length //xx的eventName监听数量
EventEmitter.listenerCount(xx, 'eventName')//同上，xx的eventName监听数量

【实例】

代码：

var EventEmitter = require('events').EventEmitter
var life = new EventEmitter()
life.setMaxListeners(11)
function fun1(who){
    console.log(who+'1');
}
life.on('a',fun1)
life.on('a',function(who){
    console.log(who+'2');
})
life.on('a',function(who){
    console.log(who+'3');
})
life.on('a',function(who){
    console.log(who+'4');
})
life.on('a',function(who){
    console.log(who+'5');
})
life.on('a',function(who){
    console.log(who+'6');
})
life.on('a',function(who){
    console.log(who+'7');
})
life.on('a',function(who){
    console.log(who+'8');
})
life.on('a',function(who){
    console.log(who+'9');
})
life.on('a',function(who){
    console.log(who+'10');
})
life.on('a',function(who){
    console.log(who+'11');
})
var hasAListener = life.emit('a','zdy');
console.log("初始是否被监听："+ hasAListener);
console.log("初始监听数量：" + life.listeners('a').length); 
life.removeListener('a',fun1); //移除监听
hasAListener = life.emit('a','zdy');
console.log("移除一个监听之后的监听数量："+life.listeners('a').length); 
console.log("移除一个监听之后是否被监听："+ hasAListener);
life.removeAllListeners('a'); //移除全部监听
hasAListener = life.emit('a','zdy');
console.log("移除全部监听之后的监听数量："+life.listeners('a').length); 
console.log("移除所有监听之后是否被监听："+ hasAListener);
console.log(EventEmitter.listenerCount(life, 'a'));

结果：

zdy1
zdy2
zdy3
zdy4
zdy5
zdy6
zdy7
zdy8
zdy9
zdy10
zdy11
初始是否被监听：true
初始监听数量：11
zdy2
zdy3
zdy4
zdy5
zdy6
zdy7
zdy8
zdy9
zdy10
zdy11
移除一个监听之后的监听数量：10
移除一个监听之后是否被监听：true
移除全部监听之后的监听数量：0
移除所有监听之后是否被监听：false
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