自定义事件

<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title> 自定义事件 </title>

</head>
<body>

</body>
</html>
<script>
function EventTarget(){
    this.handlers = {};
}

EventTarget.prototype = {
    constructor : EventTarget,
    // 注册事件
    addHandler : function(type,handler){
        if(typeof this.handlers[type] == 'undefined') this.handlers[type] = [];
        this.handlers[type].push(handler);
    },
    // 触发事件
    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);
            }
        }
    },
    // 移除事件
    removeHandler : function(type,handler){
        if(this.handlers[type] instanceof 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 fn_message(event){
    alert(event.message);
}

var target = new EventTarget();
target.addHandler('message',fn_message);
target.fire({type:'message',message:'I love javascript'});
target.removeHandler('message',fn_message);
target.fire({type:'message',message:'I love javascript'});

</script>