如何防止鼠标移出移入子元素触发mouseout和mouseover事件

js代码：

function isMouseLeaveOrEnter(e, handler) {
var reltg=e.relatedTarget?e.relatedTarget:e.type=='mouseout'?e.toElement:e.fromElement;
while (reltg && reltg != handler){
reltg = reltg.parentNode;
}
return (reltg != handler);
}