返回对象在当前级别中是第几个元素的实现代码

//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 
//<SPAN class=sep>2010-08-26 15:13:55</SPAN> 
function prev(elem,cont) { 
if(!cont){cont=1} 
elem = elem.previousSibling; 
if(elem){return prev(elem,(cont+1))} 
return cont 
} 

prev($("ext-gen232"))