ajax的异步请求获取数据

  //将选中的id传到后台以键值对的形式缓存到CacheUtilts中存起来
        function cacheIds(ids){
        var key = "";
            $.ajax(
                     {
                        url: "${appRoot}/log/cacheMenueIds.action",
                        async: false,
                        type : "POST",//传递放式，post传递参数无限制
                        data: "ids="+ids,
                        success: function(data){
                            key = data.idsKey;
                         },
                         dataType: "json"
                     });
            return key;         
        }