大家应该还记得dispatch方法中有这么一段代码：
event = jQuery.event.fix( event );
event的修复是在fix这个方法中的，而在fix中是通过 new jQuery.Event( originalEvent )来重新构建event对象的，
同时还修复了一些属性值，请看
fix: function( event ) { if ( event[ jQuery.expando ] ) { // 如果event已经被修正则直接返回 return event; } // Create a writable copy of the event object and normalize some properties var i, prop, copy, type = event.type, originalEvent = event, fixHook = this.fixHooks[ type ]; /* 获取需从原生event对象获取的属性值 fixHooks中看看有没有对应事件类型的修正 如果没有，则从mouseHooks或者是keyhooks中取，如果都没有就设置为空对象 * */ if ( !fixHook ) { this.fixHooks[ type ] = fixHook = rmouseEvent.test( type ) ? this.mouseHooks : rkeyEvent.test( type ) ? this.keyHooks : {}; } // 需要复制的属性key数组 copy = fixHook.props ? this.props.concat( fixHook.props ) : this.props; event = new jQuery.Event( originalEvent ); // 新建jQuery的event对象 /* 从原生event对象赋值属性到新event对象 * */ i = copy.length; while ( i-- ) { prop = copy[ i ]; event[ prop ] = originalEvent[ prop ]; } // Support: IE<9 // Fix target property (#1925) // 修正event.target if ( !event.target ) { event.target = originalEvent.srcElement || document; } // Support: Chrome 23+, Safari? // Target should not be a text node (#504, #13143) /* 如果event.target为文本节点则target指向其父节点 * */ if ( event.target.nodeType === 3 ) { event.target = event.target.parentNode; } // Support: IE<9 // For mouse/key events, metaKey==false if it's undefined (#3368, #11328) /* * 如果.metaKey == undefined 则返回false * 这是以一种巧妙的写法 * !!undefined ==> false * !!null ==> false * !!"" ==> false * !!"a" ==> true */ event.metaKey = !!event.metaKey; return fixHook.filter ? fixHook.filter( event, originalEvent ) : event; }, mouseHooks: { props: "button buttons clientX clientY fromElement offsetX offsetY pageX pageY screenX screenY toElement".split(" "), filter: function( event, original ) { var body, eventDoc, doc, button = original.button, fromElement = original.fromElement; // Calculate pageX/Y if missing and clientX/Y available /* 修正pageX,pageY属性值 * */ if ( event.pageX == null && original.clientX != null ) { eventDoc = event.target.ownerDocument || document; doc = eventDoc.documentElement; body = eventDoc.body; event.pageX = original.clientX + ( doc && doc.scrollLeft || body && body.scrollLeft || 0 ) - ( doc && doc.clientLeft || body && body.clientLeft || 0 ); event.pageY = original.clientY + ( doc && doc.scrollTop || body && body.scrollTop || 0 ) - ( doc && doc.clientTop || body && body.clientTop || 0 ); } /* 修正relatedTarget 该值为触发事件时的来源元素 * */ // Add relatedTarget, if necessary if ( !event.relatedTarget && fromElement ) { event.relatedTarget = fromElement === event.target ? original.toElement : fromElement; } // Add which for click: 1 === left; 2 === middle; 3 === right // Note: button is not normalized, so don't use it /* 修正which属性，鼠标左键，右键，中键 chrome:1 === left; 2 === middle; 3 === right ie没有which只有button 1 === left === (button == 1); 2 === middle === (button == 4); 3 === right === (button == 2) * */ if ( !event.which && button !== undefined ) { event.which = ( button & 1 ? 1 : ( button & 2 ? 3 : ( button & 4 ? 2 : 0 ) ) ); } return event; }
},
今天有些焦躁，唉！