发布订阅者模式
<script>
// 事件触发器
class EventEmitter {
constructor () {
// { 'click': [fn1, fn2], 'change': [fn] }
this.subs = Object.create(null)
}
// 注册事件
$on (eventType, handler) {
this.subs[eventType] = this.subs[eventType] || []
this.subs[eventType].push(handler)
}
// 触发事件
$emit (eventType) {
if (this.subs[eventType]) {
this.subs[eventType].forEach(handler => {
handler()
})
}
}
}
// 测试
let em = new EventEmitter()
em.$on('click', () => {
console.log('click1')
})
em.$on('click', () => {
console.log('click2')
})
em.$emit('click')
</script>