今天我们来学习jQuery.Event对象。jQuery为了添加自己的处理机制，及可以传递用户自定义数据，于是Event对象就出世了。
1 jQuery.Event = function( src, props ) { 2 // instanceof 用于判断一个变量是否某个对象的实例 3 if ( !( this instanceof jQuery.Event) ) { 4 return new jQuery.Event( src, props ); 5 } 6 7 // Event object 8 if ( src && src.type ) { 9 /* 10 如果是event对象 11 * */ 12 this.originalEvent = src; // 将原生的event对象存于Event中 13 this.type = src.type; // 事件类型 14 15 // Events bubbling up the document may have been marked as prevented 16 // by a handler lower down the tree; reflect the correct value. 17 /* 18 修正isDefaultPrevented方法 19 * */ 20 this.isDefaultPrevented = src.defaultPrevented || 21 src.defaultPrevented === undefined && 22 // Support: IE < 9, Android < 4.0 23 src.returnValue === false ? 24 returnTrue : 25 returnFalse; 26 27 // Event type 28 } else { 29 // 如果event是事件名称 30 this.type = src; 31 } 32 33 // Put explicitly provided properties onto the event object 34 // 添加自定义属性 35 if ( props ) { 36 jQuery.extend( this, props ); 37 } 38 39 // Create a timestamp if incoming event doesn't have one 40 this.timeStamp = src && src.timeStamp || jQuery.now(); // 添加时间戳 41 42 // Mark it as fixed 43 this[ jQuery.expando ] = true; // 标识event已被处理过 44 }; 45 46 jQuery.Event.prototype = { 47 isDefaultPrevented: returnFalse, 48 isPropagationStopped: returnFalse, 49 isImmediatePropagationStopped: returnFalse, 50 51 preventDefault: function() { 52 /* 53 修正【阻止默认事件】 54 * */ 55 var e = this.originalEvent; // 取出原生evnet 56 57 this.isDefaultPrevented = returnTrue; 58 if ( !e ) { 59 return; 60 } 61 62 // If preventDefault exists, run it on the original event 63 if ( e.preventDefault ) { 64 e.preventDefault(); 65 66 // Support: IE 67 // Otherwise set the returnValue property of the original event to false 68 } else { 69 e.returnValue = false; 70 } 71 }, 72 stopPropagation: function() { 73 /* 74 修正【停止冒泡】 75 * */ 76 var e = this.originalEvent; // 取出原生evnet 77 78 this.isPropagationStopped = returnTrue; 79 if ( !e ) { 80 return; 81 } 82 // If stopPropagation exists, run it on the original event 83 if ( e.stopPropagation ) { 84 e.stopPropagation(); 85 } 86 87 // Support: IE 88 // Set the cancelBubble property of the original event to true 89 e.cancelBubble = true; 90 }, 91 stopImmediatePropagation: function() { 92 /* 93 修正【stopImmdiatePropagation】 94 stopImmediatePropagation 的功能比stopPropagation 多一些， 95 除了可以阻止事件冒泡之外，还可以把这个元素绑定的同类型事件也阻止了。 96 * */ 97 var e = this.originalEvent; 98 99 this.isImmediatePropagationStopped = returnTrue; 100 101 if ( e && e.stopImmediatePropagation ) { 102 e.stopImmediatePropagation(); 103 } 104 105 this.stopPropagation(); 106 }
107 };
Event方法主要是对兼容性做了处理看注释应该就明白了！