mootools 鼠标事件目标
就mootools鼠标事件而言，“目标”、“相关目标”和“fromelement”之间有什么区别？
例如，在下面的代码中为什么没有使用 target 以及为什么有 ||涉及？
'mouseenter':function(e){
var reltar = e.relatedTarget || e.fromElement;
}
whats is the difference between a "target" a "relatedTarget" and a "fromelement" in terms of a mootools mouse event?
for example in the following code why is target not being used and why is there a || involved?
'mouseenter':function(e){
var reltar = e.relatedTarget || e.fromElement;
}
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基本上，
目标是事件正在分派的元素。即latedTarget是鼠标悬停/输入时鼠标来自的元素。fromelement是 MS 实现latedTarget功能的方法。因此，是一种跨浏览器的方式来检测鼠标来自哪个元素。
Basically,
The
targetis the element the event is dispatching on. i.e.The
relatedTargetis the element the mouse came from in case of mouseover/enter.fromelementis the MS way to implement whatrelatedTargetdoes. Therefore,is a cross-browser way to detect what element the mouse came from.
W3C 规定
event.latedTarget是mouseover事件中鼠标来自的元素，或者是鼠标在mouseout事件中转到。但是，IE 对于这两种情况使用两个单独的属性：
event.fromElement是mouseover< 中鼠标来自的元素/code> 事件，而event.toElement是鼠标在mouseout事件中转到的元素。您可以在 Peter-Paul Koch 的以下页面上找到更多详细信息和一些示例（那里有非常好的内容）：
http://www.quirksmode.org/js/events_mouse.html
W3C says that
event.relatedTargetis the element where mouse comes from in amouseoverevent, or the element that the mouse goes to in amouseoutevent.However, IE uses two separate properties for those two cases:
event.fromElementis the element the mouse comes from in amouseoverevent, whileevent.toElementis the element the mouse goes to in amouseoutevent.You can find more details and some examples on the following page by Peter-Paul Koch (very good content there):
http://www.quirksmode.org/js/events_mouse.html