转自《高级javascript程序设计第二版》。
在看YUI的时候，本来对自定义事件的了解不是那么深的，但看了《高》之后，对这个功能有了更深入的了解。的确是个很棒的思路。
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function EventTarget(){
this.handlers = {};
}
EventTarget.prototype = {
constructor : EventTarget,
adddHandler : function(type,handler){
if (typeof this.handlers[type] == "undefined"){
this.handlers[type] = [];
}
this.handlers[type].push(handler);
},
fire : function(event){
if(!event.target){
event.target = this;
}
if (this.handlers[event.type] instanceof Array){
var handlers = this.handlers[event.type];
for ( var i=0,len = handlers.length;i<len;i++){
handlers[i](event);
}
}
},
removeHandler : function(type,handler){
if (this.handlers[type] instance of Array){
var handlers = this.handlers[type];
for ( var i=0,len=handlers.length;i<len;i++){
if (handlers[i] === handler){
break;
}
}
handlers.splice(i,1);
}
}
};
function handleMessage(event){
alert("Message received: " + event.message);
}
var target = new EventTarget();
target.addHandler("message",handleMessage);
target.fire({type : "message",message : "hello world"});
target.removeHandler("message",handleMessage);
function Person(name,age){
EventTarget.call(this);
this.name = name;
this.age = age;
}
extend(Person,EventTarget);
Person.prototype.say = function(message){
this.fire({type:"message",message:message});
}
var person = new Person("adang",26);
person.addHandler("message",handleMessage);
person.say("Hi there");