function classChange{
    alert("fdfd");
    var tmpObj = document.getElementsByTagName('div');
    if(!tmpObj){return;}
    for(var i = 0; i<tmpObj.length;i++ ){
    if(tmpObj[i].onMouseOver){tmpObj[i].className="ban_2";}
    else{tmpObj[i].className = "ban_1";}
    }

改变样式