发布订阅模式 - zymonody - 沸点 - 掘金

2年前

#每日一题# 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, 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]
}
}
}
}

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