实现一个EventEmitter类
class EventEmitter {
constructor() {
this._events = {}
}
on(eventName,callback) {
let callbacks = eventName
in this._events ? this._events[eventName] : [];
callbacks.push(callback)
this._events[eventName] = callbacks
}
emit(eventName,...args) {
const callbacks = this._events[eventName]
callbacks.map(cb => {
cb(...args)
})
}
off(eventName, callback) {
if (!eventName
in this._events)
return
let callbacks = this._events[eventName]
let index = callbacks.indexOf(callback)
callbacks.splice(index, 1)
}
}
const emitter = new EventEmitter()
const sayHi = (name) => console.log(`Hello
${name}`)
emitter.on(
'hi', sayHi)
emitter.emit(
'hi',
'nwd')
emitter.off(
'hi', sayHi)
emitter.emit(
'hi',
'您好')
作者：李赫feixuan
链接：https://juejin.im/post/5b39e42be51d4558c329ebc5
来源：掘金
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。
