javascript 事件处理示例分享

废话少说，直接奉上示例代码：

<script type="text/javascript">

    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));

        });

    });

</script>

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：

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。