The essential differences between mouseenter/mouseleave and mouseover/mouseout are described on the Internet. However, the explanations are in the fog of the cloud, their difference it differs in that it doesn't bubble and that it isn't sent when the pointer is moved from one of its descendants 'physical space to its own physical space is introduced from mozilla.org
The above sentence is separated by different colors for easy understanding.In essence, it is embodied in bubbles..
You can use the following two examples to enhance your impression and test the environment Firefox + Firebug.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
References:
Http://www.cnblogs.com/libmw/articles/2600747.html