可以看到無論是執行效率還是內存占用myEvent都比有一定優勢，這是可能是由於jQuery事件機制過於強大導致其性能的損耗。
測試樣本：http://www.planeart.cn/demo/myEvent/
二、擴展自定義事件機制
jQuery是可以自定義事件的，它用一個special命名空間存儲自定義事件，我在上面代碼的基礎上模仿jQuery自定義事件機制，並把其著名的ready事件與另外一個jQuery hashchange事件插件移植過來。
這兩個自定義事件非常重要，ready事件可以在DOM就緒給元素綁定事件，比傳統使用window.onload要快很多；hashchange事件可以監聽錨點改變，常用於解決AJAX歷史記錄問題，如Twitter新版本就就采用此處理AJAX，使用錨點機制除了可以提高AJAX應用程序的用戶體驗外，如果按照一定規則還能被google索引到。
當然，我前面文章實現的imgReady事件也可以通過此擴展進來，稍後更新。
復制代碼 代碼如下:
// myEvent 0.2.2
// 2011.04.07 - TangBin - planeart.cn - MIT Licensed
/**
* 事件框架
* @namespace
* @see http://www.planeart.cn/?p=1285
*/
var myEvent = (function () {
var _ret, _name,
_fid = 1,
_guid = 1,
_time = (new Date).getTime(),
_nEid = '{$eid}' + _time,
_nFid = '{$fid}' + _time,
_DOM = document.addEventListener,
_noop = function () {},
_create = function (guid) {
return function (event) {
event = myEvent.fix(event || window.event);
var type = (event || (event = document.event)).type,
elem = _cache[guid].elem,
data = arguments,
events = _cache[guid].events[type],
i = 0,
length = events.length;
for (; i < length; i ++) {
if (events[i].apply(elem, data) === false) event.preventDefault();
};
event = elem = null;
};
},
_cache = {/*
1: {
elem: (HTMLElement),
events: {
click: [(Function), (..)],
(..)
},
listener: (Function)
},
(..)
*/};
var API = function () {};
API.prototype = {
/**
* 事件綁定
* @param {HTMLElement} 元素
* @param {String} 事件名
* @param {Function} 要綁定的函數
*/
bind: function (elem, type, callback) {
var events, listener,
guid = elem[_nEid] || (elem[_nEid] = _guid ++),
special = this.special[type] || {},
cacheData = _cache[guid];
if (!cacheData) cacheData = _cache[guid] = {
elem: elem,
listener: _create(guid),
events: {}
};
events = cacheData.events;
listener = cacheData.listener;
if (!events[type]) events[type] = [];
if (!callback[_nFid]) callback[_nFid] = _fid ++;
if (!special.setup || special.setup.call(elem, listener) === false) {
events[type].length === 0 && this.add(elem, type, listener);
};
events[type].push(callback);
},
/**
* 事件卸載
* @param {HTMLElement} 元素
* @param {String} 事件名
* @param {Function} 要卸載的函數
*/
unbind: function (elem, type, callback) {
var events, special, i, list, fid,
guid = elem[_nEid],
cacheData = _cache[guid];
if (!cacheData) return;
events = cacheData.events;
if (callback) {
list = events[type];
fid = callback[_nFid];
if (!list) return;
for (i = 0; i < list.length; i ++) {
list[i][_nFid] === fid && list.splice(i--, 1);
};
if (!list.length) this.unbind(elem, type);
} else if (type) {
special = this.special[type] || {};
if (!special.teardown || special.teardown.call(elem) === false) {
this.remove(elem, type, cacheData.listener);
};
delete events[type];
} else {
for (i in events) {
this.remove(elem, i, cacheData.listener);
};
delete _cache[guid];
};
},
/**
* 事件觸發 (注意：不會觸發浏覽器默認行為與冒泡)
* @param {HTMLElement} 元素
* @param {String} 事件名
* @param {Array} (可選)附加數據
*/
triggerHandler: function (elem, type, data) {
var guid = elem[_nEid],
cacheData = _cache[guid],
event = {
type: type,
target: elem,
currentTarget: elem,
preventDefault: _noop,
stopPropagation: _noop
};
data = data || [];
data.unshift(event);
cacheData && cacheData.events[type] && _cache[guid].listener.apply(elem, data);
try {
elem['on' + type] && elem['on' + type].apply(elem, data);
//elem[type] && elem[type]();
} catch (e) {};
},
// 自定義事件接口
special: {},
// 原生事件綁定接口
add: _DOM ? function (elem, type, listener) {
elem.addEventListener(type, listener, false);
} : function (elem, type, listener) {
elem.attachEvent('on' + type, listener);
},
// 原生事件卸載接口
remove: _DOM ? function (elem, type, listener) {
elem.removeEventListener(type, listener, false);
} : function (elem, type, listener) {
elem.detachEvent('on' + type, listener);
},
// 修正
fix: function (event) {
if (_DOM) return event;
var name,
newEvent = {},
doc = document.documentElement,
body = document.body;
newEvent.target = event.srcElement || document;
newEvent.target.nodeType === 3 && (newEvent.target = newEvent.target.parentNode);
newEvent.preventDefault = function () {event.returnValue = false};
newEvent.stopPropagation = function () {event.cancelBubble = true};
newEvent.pageX = newEvent.clientX + (doc && doc.scrollLeft || body && body.scrollLeft || 0) - (doc && doc.clientLeft || body && body.clientLeft || 0);
newEvent.pageY = newEvent.clientY + (doc && doc.scrollTop || body && body.scrollTop || 0) - (doc && doc.clientTop || body && body.clientTop || 0);
newEvent.relatedTarget = event.fromElement === newEvent.target ? event.toElement : event.fromElement;
// !!直接寫event IE導致內存洩漏，Firefox會報錯
// 偽裝event
for (name in event) newEvent[name] = event[name];
return newEvent;
}
};
return new API();
})();
// DOM就緒事件
myEvent.ready = (function () {
var readyList = [], DOMContentLoaded,
readyBound = false, isReady = false;
function ready () {
if (!isReady) {
if (!document.body) return setTimeout(ready, 13);
isReady = true;
if (readyList) {
var fn, i = 0;
while ((fn = readyList[i++])) {
fn.call(document, {});
};
readyList = null;
};
};
};
function bindReady () {
if (readyBound) return;
readyBound = true;
if (document.readyState === 'complete') {
return ready();
};
if (document.addEventListener) {
document.addEventListener('DOMContentLoaded', DOMContentLoaded, false);
window.addEventListener('load', ready, false);
} else if (document.attachEvent) {
document.attachEvent('onreadystatechange', DOMContentLoaded);
window.attachEvent('onload', ready);
var toplevel = false;
try {
toplevel = window.frameElement == null;
} catch (e) {};
if (document.documentElement.doScroll && toplevel) {
doScrollCheck();
};
};
};
myEvent.special.ready = {
setup: bindReady,
teardown: function () {}
};
if (document.addEventListener) {
DOMContentLoaded = function () {
document.removeEventListener('DOMContentLoaded', DOMContentLoaded, false);
ready();
};
} else if (document.attachEvent) {
DOMContentLoaded = function () {
if (document.readyState === 'complete') {
document.detachEvent('onreadystatechange', DOMContentLoaded);
ready();
};
};
};
function doScrollCheck () {
if (isReady) return;
try {
document.documentElement.doScroll('left');
} catch (e) {
setTimeout(doScrollCheck, 1);
return;
};
ready();
};
return function (callback) {
bindReady();
if (isReady) {
callback.call(document, {});
} else if (readyList) {
readyList.push(callback);
};
return this;
};
})();
// Hashchange Event v1.3
(function (window, undefined) {
var config = {
delay: 50,
src: null,
domain: null
},
str_hashchange = 'hashchange',
doc = document,
isIE = !-[1,],
fake_onhashchange, special = myEvent.special,
doc_mode = doc.documentMode,
supports_onhashchange = 'on' + str_hashchange in window && (doc_mode === undefined || doc_mode > 7);
function get_fragment(url) {
url = url || location.href;
return '#' + url.replace(/^[^#]*#?(.*)$/, '$1');
};
special[str_hashchange] = {
setup: function () {
if (supports_onhashchange) return false;
myEvent.ready(fake_onhashchange.start);
},
teardown: function () {
if (supports_onhashchange) return false;
myEvent.ready(fake_onhashchange.stop);
}
};
/** @inner */
fake_onhashchange = (function () {
var self = {},
timeout_id, last_hash = get_fragment(),
/** @inner */
fn_retval = function (val) {
return val;
},
history_set = fn_retval,
history_get = fn_retval;
self.start = function () {
timeout_id || poll();
};
self.stop = function () {
timeout_id && clearTimeout(timeout_id);
timeout_id = undefined;
};
function poll() {
var hash = get_fragment(),
history_hash = history_get(last_hash);
if (hash !== last_hash) {
history_set(last_hash = hash, history_hash);
myEvent.triggerHandler(window, str_hashchange);
} else if (history_hash !== last_hash) {
location.href = location.href.replace(/#.*/, '') + history_hash;
};
timeout_id = setTimeout(poll, config.delay);
};
isIE && !supports_onhashchange && (function () {
var iframe,iframe_src, iframe_window;
self.start = function () {
if (!iframe) {
iframe_src = config.src;
iframe_src = iframe_src && iframe_src + get_fragment();
iframe = doc.createElement('<IFRAME title=empty style="DISPLAY: none" tabIndex=-1 src="' + (iframe_src || 'javascript:0') + '"></IFRAME>');
myEvent.bind(iframe, 'load', function () {
myEvent.unbind(iframe, 'load');
iframe_src || history_set(get_fragment());
poll();
});
doc.getElementsByTagName('html')[0].appendChild(iframe);
iframe_window = iframe.contentWindow;
doc.onpropertychange = function () {
try {
if (event.propertyName === 'title') {
iframe_window.document.title = doc.title;
};
} catch (e) {};
};
};
};
self.stop = fn_retval;
/** @inner */
history_get = function () {
return get_fragment(iframe_window.location.href);
};
/** @inner */
history_set = function (hash, history_hash) {
var iframe_doc = iframe_window.document,
domain = config.domain;
if (hash !== history_hash) {
iframe_doc.title = doc.title;
iframe_doc.open();
domain && iframe_doc.write('<SCRIPT>document.domain="' + domain + '"</SCRIPT>');
iframe_doc.close();
iframe_window.location.hash = hash;
};
};
})();
return self;
})();
})(this);
ready事件是偽事件，調用方式：
復制代碼 代碼如下:myEvent.ready(function () {
//[code..]
});
hashchange事件可以采用標准方式綁定：
復制代碼 代碼如下: myEvent.bind(window, 'hashchange', function () {
//[code..]
});
這裡有一些文章值得閱讀：
javascript 跨浏覽器的事件系統(司徒正美。他博客有一系列的講解)
更優雅的兼容（BELLEVE INVIS）