JavaScript 实现自定义事件监听：以 Classroom 为例

JavaScript 自定义事件处理机制

例如，我们定义了一个 Classroom 对象，并设定一个事件：当教室内人数超过 60 人时，触发名为 onFull 的事件。具体定义如下：

var Classroom=function()
{ 
this.numberOfPeople=0;
this.onFull=null;
this.peopleEnter=function(number)
{ 
this.numberOfPeople+=number;
if(this.numberOfPeople>60&&this.onFull!=null)
{ 
this.onFull(this.numberOfPeople);
} 
} 
} 
function show1(number)
{ 
alert("教室里有"+number+"人");
} 
function show2(number)
{ 
alert("教室里超出了"+(number-60)+"人");
} 
var classroom1=new Classroom();
classroom1.onFull=show1;
classroom1.peopleEnter(30);
classroom1.peopleEnter(32);
classroom1.onFull=show2;
classroom1.peopleEnter(34);