应用于cookie

    var aA=document.getElementsByTagName(‘a‘);    
    
    //使用
    var index=getCookie(‘page_index‘);
    if(index){
        tab(index);
    }
    
    for(var i=0; i<aA.length; i++){
        (function(index){
            aA[i].onclick=function(){
                tab(index);    
                
                //设置一个cookie
                setCookie(‘page_index‘,index,10);
            }
        })(i);
    }
    
    function tab(n){
        for(var i=0; i<aA.length; i++){
            aA[i].className=‘‘;
        }
        aA[n].className=‘on‘;    
    }
};

<a href="javascript:;" class="on">0</a>
<a href="javascript:;">1</a>
<a href="javascript:;">2</a>
<a href="javascript:;">3</a>
<a href="javascript:;">4</a>

a{ padding:10px 15px; background:#399; color:#fff; text-decoration:none;}
a.on{ background:#f60;}