修改页面select下拉框，selected之前选择的，遍历表数据

1前台jsp触发
2//渠道下拉框  
function getChanNameEdit() {  
var selectNext =$("#chanId");
$.ajax({  
                  type: "post",    
                  contentType:"application/json",    
                  url : "getChanName.do",  
                  dataType: 'json',
                  success: function(data){     
                  var data = eval('(' + data + ')');   
                  if(data.length!="" && data.length!=null){   
                        for ( var i = 0; i < data.length; i++) {
                            var strSelected = "";
                            var html = "<option value='"+data[i].chan_id+"' ";
                            if(chan == data[i].chan_id){
                               strSelected = "selected";
                            }
                            html+=strSelected+">";
                            html+=data[i].chan_name+"</option>";
                           selectNext.append(html);
                        }  
                   }else{  
                               var a = 0;
                          selectNext.append("<option value="+a+">全部</option>");  
                  }  
                     },
                  error: function(XMLHttpRequest, textStatus, errorThrown) {
                         alert(XMLHttpRequest.status);
                         alert(XMLHttpRequest.readyState);
                         alert(textStatus);
                           }
});
}