返回对象在当前级别中是第几个元素

//语法：prev(element)
//参数：element对象
//返回：对象在当前级别中是第几个元素,从1开始
//2010-08-26 15:13:55 

function prev(elem,cont) {
    if(!cont){cont=1}
    elem = elem.previousSibling;
    if(elem){return prev(elem,(cont+1))}
    return cont
}

prev($("ext-gen232"))