Dean Edwards大神写的addEvent库
直接晒代码：
1 // written by Dean Edwards, 2005 2 // with input from Tino Zijdel, Matthias Miller, Diego Perini 3 4 // http://dean.edwards.name/weblog/2005/10/add-event/ 5 6 function addEvent(element, type, handler) { 7 if (element.addEventListener) { 8 element.addEventListener(type, handler, false); 9 } else { 10 // assign each event handler a unique ID 11 if (!handler.$$guid) handler.$$guid = addEvent.guid++; 12 // create a hash table of event types for the element 13 if (!element.events) element.events = {}; 14 // create a hash table of event handlers for each element/event pair 15 var handlers = element.events[type]; 16 if (!handlers) { 17 handlers = element.events[type] = {}; 18 // store the existing event handler (if there is one) 19 if (element["on" + type]) { 20 handlers[0] = element["on" + type]; 21 } 22 } 23 // store the event handler in the hash table 24 handlers[handler.$$guid] = handler; 25 // assign a global event handler to do all the work 26 element["on" + type] = handleEvent; 27 } 28 }; 29 // a counter used to create unique IDs 30 addEvent.guid = 1; 31 32 function removeEvent(element, type, handler) { 33 if (element.removeEventListener) { 34 element.removeEventListener(type, handler, false); 35 } else { 36 // delete the event handler from the hash table 37 if (element.events && element.events[type]) { 38 delete element.events[type][handler.$$guid]; 39 } 40 } 41 }; 42 43 function handleEvent(event) { 44 var returnValue = true; 45 // grab the event object (IE uses a global event object) 46 event = event || fixEvent(((this.ownerDocument || this.document || this).parentWindow || window).event); 47 // get a reference to the hash table of event handlers 48 var handlers = this.events[event.type]; 49 // execute each event handler 50 for (var i in handlers) { 51 this.$$handleEvent = handlers[i]; 52 if (this.$$handleEvent(event) === false) { 53 returnValue = false; 54 } 55 } 56 return returnValue; 57 }; 58 59 function fixEvent(event) { 60 // add W3C standard event methods 61 event.preventDefault = fixEvent.preventDefault; 62 event.stopPropagation = fixEvent.stopPropagation; 63 return event; 64 }; 65 fixEvent.preventDefault = function() { 66 this.returnValue = false; 67 }; 68 fixEvent.stopPropagation = function() { 69 this.cancelBubble = true; 70 };
