1 //自定义事件
2 function EventTarget() {
3 this.handlers = {};
4 }
5 EventTarget.prototype = {
6 constructor: EventTarget,
7 //注册
8 addHandler: function(type, handler) {
9 if (typeof this.handlers[type] == "undefined") {
10 this.handlers[type] = [];
11 }
12 this.handlers[type].push(handler);
13 },
14 //触发
15 fire: function(event) {
16 if (!event.target) {
17 event.target = this;
18 }
19 if (this.handlers[event.type] instanceof Array) {
20 var handlers = this.handlers[event.type];
21 for (var i = 0, len = handlers.length; i < len; i++) {
22 handlers[i](event);
23 }
24 }
25 },
26 //注销
27 removeHandler: function(type, handler) {
28 if (this.handlers[type] instanceof Array) {
29 var handlers = this.handlers[type];
30 for (var i = 0, len = handlers.length; i < len; i++) {
31 if (handlers[i] === handler) {
32 break;
33 }
34 }
35 handlers.splice(i, 1);
36 }
37 }
38 };
1 //使用方法
2 function handleMessage(event) {
3 alert("Message received: " + event.message);
4 }
5 //创建一个新对象
6 var target = new EventTarget();
7 //添加一个事件处理程序
8 target.addHandler("message", handleMessage);
9 //触发事件
10 target.fire({
11 type: "message",
12 message: "Hello world!"
13 });
14 //删除事件处理程序
15 target.removeHandler("message", handleMessage);
16 //再次，应没有处理程序
17 target.fire({
18 type: "message",
19 message: "Hello world!"
20 });
