ts实现发布订阅

interface CacheProps {
    [key: string]: Array<((data:unknown) => void)>;
}

class Observer {
    private caches:CacheProps = {};
    on(eventName: string,fn:((data?:unknown) => void)) {
        this.caches[eventName] = this.caches[eventName]?this.caches[eventName]:[];
        this.caches[eventName].push(fn);
    }
    emit(eventName: string,data?:unknown) {
        if(this.caches[eventName]) {
            this.caches[eventName].forEach((fn)=> {
                fn(data);
            })
        } else {
            return {
                flag: false,
                errMsg: "不存在该函数"
            }
        }
    }
    off(eventName:string,fn:((data?:unknown) => void)) {
        if(this.caches[eventName]) {
            const newCaches = fn?this.caches[eventName].filter(e => e !== fn):[];
            this.caches[eventName] = newCaches;
        }
    }
}
function a() {
    console.log(4);
}
const obj:Observer = new Observer();
obj.on("aaa",()=>{console.log(3)});
obj.on("aaa",()=>{console.log(3)});
obj.on("aaa",a);
console.log(obj)
obj.off("aaa",a);
obj.emit("aaa");