loginStateShow.className=' ';     是否不用类名清空，按下一句语句格式效果也是相同的？

       var id=this.id;
       stateList.style.display='none';
        stateTxt.innerHTML=getByClass('stateSelect_text',id)[0].innerHTML;      
      //  loginStateShow.className=' ';         
        loginStateShow.className='login-state-show '+id;