代码如下:

function EventUtil() {
var _self = this;
///添加事件
var addEvent = (function () {
if (document.addEventListener) {
return function (el, type, fn) {
el.addEventListener(type, fn, false);
}
} else {
return function (el, type, fn) {
el.attachEvent("on" + type, function () {
return fn.call(el, window.event);
});
}
}
})();
///添加属性改变事件
var addPropertyChangeEvent = function (obj, fn) {
if (window.ActiveXObject) {
obj.onpropertychange = fn;
} else {
obj.addEventListener("input", fn, false);
}
}
//移除事件
var removeEvent = function (obj, type, fn) {
if (obj.removeEventListener) {
obj.removeEventListener(type, fn, false);
} else if (obj.detachEvent) {
obj.detachEvent("on" + type, obj["on" + type + fn]);
obj["on" + type + fn] = null;
}
}
//加载事件
var loadEvent = function (fn) {
var oldonload = window.onload;
if (typeof oldonload != "function") {
window.onload = fn;
} else {
window.onload = function () {
oldonload();
fn();
}
}
}
//阻止事件
var stopEvent = function (e) {
e = e || window.event;
if (e.preventDefault) {
e.preventDefault();
e.stopPropagation();
} else {
e.returnValue = false;
e.cancelBubble = true;
}
}
//如果仅仅是阻止事件冒泡
var stopPropagation = function (e) {
e = e || window.event;
if (!+"\v1") {
e.cancelBubble = true;
} else {
e.stopPropagation();
}
}
//取得事件源对象
var getEvent1 = function (e) {
e = e || window.event;
var obj = e.srcElement ? e.srcElement : e.target;
return obj;
}
//取得事件源对象
var getEvent2 = function (e) {
if (window.event) return window.event;
var c = getEvent2.caller;
while (c.caller) {
c = c.caller;
}
return c.arguments[0];
}
//或者这个功能更强大
var getEvent3 = function (e) {
var e = e || window.event;
if (!e) {
var c = this.getEvent3.caller;
while (c) {
e = c.arguments[0];
if (e && (Event == e.constructor || MouseEvent == e.constructor)) {
break;
}
c = c.caller;
}
}
var target = e.srcElement ? e.srcElement : e.target,
currentN = target.nodeName.toLowerCase(),
parentN = target.parentNode.nodeName.toLowerCase(),
grandN = target.parentNode.parentNode.nodeName.toLowerCase();
return [e, target, currentN, parentN, grandN];
}

_self.addEvent = addEvent;
_self.addPropertyChangeEvent = addPropertyChangeEvent;
_self.removeEvent = removeEvent;
_self.loadEvent = loadEvent;
_self.stopEvent = stopEvent;
_self.stopPropagation = stopPropagation;
_self.getEvent1 = getEvent1;
_self.getEvent2 = getEvent2;
_self.getEvent3 = getEvent3;
}
var eventUtil = new EventUtil();
eventUtil.loadEvent(function () {
eventUtil.addEvent(document, "click", function (e) {
alert(eventUtil.getEvent3(e));
});
eventUtil.addPropertyChangeEvent(document,function(e){
alert(eventUtil.getEvent3(e));
});
});

javascript事件处理分为三个阶段：捕获 - 处理 - 起泡。

以点击按钮为例：
捕获阶段：由外层到内层，首先调用给Window注册的click捕获阶段监听方法，然后document、body、一层层的父节点，一直到按钮本身。

处理阶段：调用按钮本身的click监听方法。

起泡阶段：从按钮开始，从内层到外层，依次调用各级父节点的起泡阶段监听方法，直到Window。

但是，对于IE8及更低版本IE，不支持捕获阶段，因此捕获阶段的事件监听目前尚不通用。

通常的事件处理方法形式为：

代码如下:
function eventHandler(e) {
e = e || window.event;
var target = e.target || e.srcElement;
... ...

}

e为事件对象，当事件触发时，作为参数传进来，但对于IE8及更低版本IE不适用，只能通过全局的event变量访问，好在不会出现同时处理两个事件的情况。