请问这个javascript函数是什么意思,急!
<SCRIPT language='javascript'>
function showmenu_item(sid)
{
which = eval("menu_item" + sid);
if (which.style.display == "none")
{
var i = 2
while(i<9){
eval("menu_item"+ i +".style.display=\"none\";");
eval("menuTitle"+ i +".background=\"images/manage/title_bg_show.gif\";");
i++;
}
eval("menu_item" + sid + ".style.display=\"\";");
eval("menuTitle"+ sid + ".background=\"images/manage/title_bg_hide.gif\";")
}else{
eval("menu_item" + sid + ".style.display=\"none\";");
eval("menuTitle"+ sid + ".background=\"images/manage/title_bg_show.gif\";")
}
}
</SCRIPT>