观察者模式


<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>观察模式例子</title>
</head>
<body>
	
</body>
<script type="text/javascript">
	var Events = function() {
		var obj = {};
		obj.stack=[];
		var listen = function( key, eventfn ) { //事件消息队列
			var stack = obj[key] ? obj[key] : (obj[ key ] = []);//1.在obj对象上添加盒子属性;2.用三目运算符解决拓展问题
			return stack.push(eventfn);
		};
		var one = function( key, eventfn ) {//添加一个唯一的订阅
			remove( key );
			return listen( key, eventfn );
		};
		var remove = function( key ) {
			return obj[key] ? obj[key].length = 0 : void 0; //取消订阅
		};
		var trigger = function() { //面试官打电话通知面试者
			var fn, stack, key;
			key = Array.prototype.shift.call( arguments );//获取arguments参数数组的第一个值
			stack = obj[key] ? obj[key] : obj[key] = [];
			for ( var i = 0,len = stack.length; i < len; i++ ) {
				fn = stack[i];
				if (fn)
				{
					fn.apply(this,arguments);
				}
			}
		}
		return {
			listen: listen,
			one: one,
			remove: remove,
			trigger: trigger
		}
	}	
	//订阅者
	var adultTv = Events();
	adultTv.listen( 'play',(data)=> {return alert("今天是谁的电影:" + data.name)})

	//发布者
	adultTv.trigger('play',{'name': "刘德华"});
</script>
</html>