事件总线-发布订阅模式
# 事件总线-发布订阅模式
class EventEmitter {
constructor() {
this.cache = {}
}
on(name, fn) {
if (this.cache[name]) {
this.cache[name].push(fn)
} else {
this.cache[name] = [fn]
}
}
off(name, fn) {
const tasks = this.cache[name]
if (tasks) {
const index = tasks.findIndex((f) => f === fn || f.callback === fn)
if (index >= 0) {
tasks.splice(index, 1)
}
}
}
emit(name) {
if (this.cache[name]) {
// 创建副本,如果回调函数内继续注册相同事件,会造成死循环
const tasks = this.cache[name].slice()
for (let fn of tasks) {
fn();
}
}
}
emit(name, once = false) {
if (this.cache[name]) {
// 创建副本,如果回调函数内继续注册相同事件,会造成死循环
const tasks = this.cache[name].slice()
for (let fn of tasks) {
fn();
}
if (once) {
delete this.cache[name]
}
}
}
}
// 测试
const eventBus = new EventEmitter()
const task1 = () => { console.log('task1'); }
const task2 = () => { console.log('task2'); }
eventBus.on('task', task1)
eventBus.on('task', task2)
setTimeout(() => {
eventBus.emit('task')
}, 1000)
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