jquery ajax 异步数据交换

function addTopKeyWords(){
// alert(num);
var topWords = $('#topWordsInput').val();
if(topWords ==""){
$.messager.alert('系统警告',mess.topWords,'warning');
return false;
}else{
      $.ajax({
async: true,
    type: "POST",     
    url: "${basePath}secure/AddTopKeyWords.action?topWords="+encodeURIComponent(topWords)+"&columnId=${columnId}", 
    success: function(data){
   // alert(data);
    var mess = eval('('+data+')');
    $('#showTopWords').html(mess.topWords);
            } 
});
      return false;
}
}