obj.onclick = fn1;
obj.onclick = fn2;
...

function bindEvent(elem,type,fn){if(elem.addEventListener){elem.addEventListener(type,fn,false);}else{elem.attachEvent("on"+type,fn);}
bindEvent(obj,"click",fn1);
bindEvent(obj,"click",fn2);

function bindEvent(elem,type,fn){if(elem.addEventListener){elem.addEventListener(type,fn,false);}else{elem.attachEvent("on"+type,function(){fn.apply(elem,arguments);});}
}
bindEvent(obj,"mouseover",function(){alert(this)})

(function(win,doc){var Event = {};Event.add = function(elem,type,fn){if(doc.addEventListener){elem.addEventListener(type,fn,false);}else{var typeRef = "_" + type;if(!elem[typeRef]){elem[typeRef] = [];}var len = elem[typeRef].length;while(len-->0){if(elem[typeRef][len] === fn)return;}elem[typeRef].push(fn);elem["on"+type] = function(){len = this[typeRef].length;this[typeRef].reverse();while(len-->0){this[typeRef][len].apply(this,arguments);}this[typeRef].reverse();}}};Event.remove = function(elem,type,fn){if(doc.addEventListener){elem.removeEventListener(type,fn,false);}else{var typeRef = "_" + type;if(elem[typeRef]){var len = elem[typeRef].length;while(len-->0){if(elem[typeRef][len] === fn){elem[typeRef].splice(len,1);break;};}}}};Event.getEve = function(e){return e || win.event;};Event.target = function(e){e = this.getEve(e);return e.target || e.srcElement;};Event.preventDefault = function(e){ //阻止默认事件e = this.getEve(e);e.preventDefault ? e.preventDefault() : e.returnValue = false;};Event.stopPropagation = function(e){ //阻止冒泡e = this.getEve(e);e.stopPropagation ? e.stopPropagation() : e.cancelBubble = true;};win.Event = Event;
})(window,document);