var columnchart= new Ext.chart.ColumnChart({   
 title:'柱状图',
bacls:'Ext.chart.ColumnChart',
store:store,         
series : [{ 
     type : 'column', 
     xField:'month',
     yField : 'hits', 
     renderer: function(sprite, record, attr, index, store) {        
                     var value = record.get('hits');      
                     alert(value);           
                     if(value==max){       
                        color = 0xFF0000;            
                     }else if(value==min){            
                        color = 0x00BB00;         
                     }else{          
                        color = 0x0000FF;       
                     }            
                     return Ext.apply(attr,{fill:color}); 
                }  
      }] 
});
获取改变最大值最小值的柱子的颜色,max、min已经能获取,到renderer就跳出去了没有进function里,求大神