学习 Javascript 之EventBus Map版

class EventBus {
    
    constructor() {
        //用Map存储订阅, 格式为: key="key3" value=["O2", function, "3", function] 
        this.eventMap = new Map();
        
        //每个订阅都配一个ID
        this.busid = 0;
    }
    
    //订阅  订阅名称   订阅代码  是否一次性订阅(默认否)
    dinyue(eventName, callback,isOnece=false) {
        
        //如果Map中没有这个Key就增加,值为一个空数组
        !this.eventMap.has(eventName) && this.eventMap.set(eventName,[]);
        
        //给每个事件搭配一个ID, 如果是一次性的订阅就在ID前面加一个字面O
        const cid = (isOnece ? 'O' : '') + (this.busid++);
        
        const arrEvent = this.eventMap.get(eventName);
        //在push订阅前, 把事件ID先插到前面,用于删除订阅和判断是否为一次性订阅时使用
        arrEvent.push(cid);
        arrEvent.push(callback);
        
        //返回一个数组,第一个为订阅名称,第二个为订阅ID
        return [eventName, cid];
    }
    
    //发布,订阅名称  订阅参数
    fabu(eventName, ...args) {
        if(!this.eventMap.has(eventName)) return;
        
        //根据订阅名称得到一个数组
        const arrEvent = this.eventMap.get(eventName);
        
        //遍历数组, 直接从1开始,然后 3,5,7,9....
        for(let i=1;i<arrEvent.length;i+=2 ) {
            
            const it = arrEvent[i];
            
            //如果是Q 说明已经被取消
            if(it === 'Q') {
                console.log(eventName + "-" + arrEvent[i-1] + ": 已经被取消");
            } 
            
            //如果是O,说明已经被执行过了
            else if(it === 'O') {
                console.log(eventName + "-" + arrEvent[i-1] + ": 已经被执行");
            }
            
            //如果不是 Q, 也不是O, 就只能是函数了,安全起见还是判断一下吧
            else if(typeof it === 'function') {
                
                //执行
                it(...args);
                
                //如果订阅搭配的ID前面有一个O,说明是一次性订阅,执行后就标记为已经执行
                if(arrEvent[i-1].charAt(0) === 'O') {
                    arrEvent[i] = 'O';
                }
            }
            

        }
    }
    
    //取消
    quxiao(arrbusid) {
        //根据订阅名称得到一个数组
        const arrevent = this.eventMap.get(arrbusid[0]);
        
        
        if(arrevent === undefined) return;
        
        //查找订阅ID的index ,  把 index + 1 位置修改为 Q, 表示已经取消订阅
        arrevent[arrevent.indexOf(arrbusid[1]) + 1] = 'Q';
    }
    

}

const eb = new EventBus();
eb.dinyue("key1",(a1,a2)=>{console.log("订阅者A: " + a1 + a2)});
const key2 = eb.dinyue("key2",(a1)=>{console.log("订阅者B: " +a1)});
eb.dinyue("key3",(a1)=>{console.log("订阅者C: " + a1)},true);
eb.dinyue("key3",(a1)=>{console.log("订阅者D: " + a1)},false);

//console.log((eb));
//eventMap: Map (3)
//key "key1"
//value ["0", function] (2)
//key "key2"
//value ["1", function] (2)
//key "key3"
//value ["O2", function, "3", function] (4)

eb.fabu("key1","i am key1",",haha");
eb.fabu("key2","i am key2");

eb.quxiao(key2);
eb.fabu("key2","i am key22");

eb.fabu("key3","i am key3哈哈");
eb.fabu("key3","i am key3-1哈哈");

//订阅者A: i am key1,haha
//1449970f22d6e671c3413a9b4a068271.js:328 订阅者B: i am key2
//1449970f22d6e671c3413a9b4a068271.js:328 key2-1: 已经被取消
//1449970f22d6e671c3413a9b4a068271.js:328 订阅者C: i am key3哈哈
//1449970f22d6e671c3413a9b4a068271.js:328 订阅者D: i am key3哈哈
//1449970f22d6e671c3413a9b4a068271.js:328 key3-O2: 已经被执行
//1449970f22d6e671c3413a9b4a068271.js:328 订阅者D: i am key3-1哈哈