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！