emit

简单模拟发布订阅模式之on、once、off、emit、clear

简单模拟发布订阅模式之on、once、off、emit、clear

clasventBus{

constructor(){

={}

}

on(key,fn){

y([key])?[key].push(fn):[key]=[fn]

}

once(key,fn){

letvm=this

functioncurOnce(){

(key,fn)

(key,curOnce)

}

=fn//once函数上的标识函数：移除curOnce，同时移除fn

(key,curOnce)

}

emit(key,fn){

if(!y([key])||![key].length)return

if(typeoffn!=='function'){

[key].forEach(f=>f())

}el{

//===fn：这⾥的判断是处理once指定的函数，请看这⾥：=fn

[key].forEach(f=>(f===fn||===fn)&&fn())

}

}

off(key,fn){

if(!y([key])||![key].length)return

if(typeoffn!=='function'){

(key)

}el{

constindex=[key].findIndex(f=>f===fn||===fn)

if(index!==-1)[key].splice(index,1)

}

}

clear(key){

if([key])[key]=[]

}

}

functionaaa(){

('aaa');

}

functiononcefn(){

('oncefn');

}

functiononcefn22(){

('oncefn22');

}

constBus=neweventBus()

//测试on

//('aaa',aaa)

//('aaa',oncefn22)

//测试clear

//('aaa')

//('aaa',aaa)

//('aaa',oncefn22)

//('aaa')

//测试once

('once',oncefn)

('once',oncefn22)

//测试clear

//('once')

//('once',oncefn)

//('once',oncefn22)

('once')

('once')

//测试移除绑定的on

//('aaa',aaa)

//('aaa')

//测试移除绑定的once

//('once',oncefn22)

//('once',oncefn22)

//('Bus:',Bus);