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function addEvent(element, type, handler) {
// assign each event handler a unique ID
if (!handler.$$guid) handler.$$guid = addEvent.guid++;
// create a hash table of event types for the element
if (!element.events) element.events = {};
// create a hash table of event handlers for each element/event pair
var handlers = element.events[type];
if (!handlers) {
handlers = element.events[type] = {};
// store the existing event handler (if there is one)
if (element["on" + type]) {
handlers[0] = element["on" + type];
}
}
// store the event handler in the hash table
handlers[handler.$$guid] = handler;
// assign a global event handler to do all the work
element["on" + type] = handleEvent;
};
// a counter used to create unique IDs
addEvent.guid = 1;
function removeEvent(element, type, handler) {
// delete the event handler from the hash table
if (element.events && element.events[type]) {
delete element.events[type][handler.$$guid];
}
};
function handleEvent(event) {
// grab the event object (IE uses a global event object)
event = event || window.event;
// get a reference to the hash table of event handlers
var handlers = this.events[event.type];
// execute each event handler
for (var i in handlers) {
this.$$handleEvent = handlers[i];
this.$$handleEvent(event);
}
};
特点：
1.it performs no object detection
2.it does not use the addeventListener/attachEvent methods
3.it keeps the correct scope (the this keyword)
4.it passes the event object correctly
5.it is entirely cross-browser (it will probably work on IE4 and NS4)
6.and from what I can tell it does not leak memory
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原文地址：http://my.oschina.net/bosscheng/blog/490333
