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Event
Js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.$$handleEvent = handlers;
52. if (this.$$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.}; |
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