[求助]一个不解的语句
<div id="item"> <a href="javascript:void(0)" onMouseover="okscroll=true; godown=true" onMouseout="okscroll=false"><img src="down.gif" border="0"></a><a href="javascript:void(0)" onMouseover="okscroll=true; godown=false" onMouseout="okscroll=false"><img src="up.gif" border="0"></a> </div>
请问在这个边框中"javascript:void(0)"有何意义啊.