/*

  跨浏览器的事件处理函数

*/

var EventUtil = {

    addHandler : function(element,type,handler){

        if(element.addEventListener){

            element.addEventListener(type,handler,false);

        }else if(element.attachEvent){

            element.attachEvent('on'+type,handler);

        }else{

            element['on'+type] = handler;

        }

    },

    removeHandler : function(element,type,handler){

        if(element.removeEventListener){

            element.removeEventListener(type,handler,false);

        }else if(element.detachEvent){

            element.detachEvent('on'+type,handler);

        }else{

            element['on'+type] = null;

        }

    }

}

var btn = document.getElementById('button');

var handler = function(){

    alert('click');

};

EventUtil.addHandler(btn,'click',handler);