window.onload=function(){

var pagecount={$page_count};

document.getElementById('firsts').setAttribute('class','disabled');

document.getElementById('before').setAttribute('class','disabled');

var current=document.getElementById('before').nextSibling;

while(current.nodeType != 1){　　　　　　根据nodeType判断节点属性

current=current.nextSibling;

}

current.setAttribute('class','current');

if(pagecount==1){

document.getElementById('next').setAttribute('class','disabled');

document.getElementById('last').setAttribute('class','disabled');

}

}