即点即改

<td width="10%"><span class="num" id="<?php echo $v['cat_id'] ?>"><?php echo $v['measure_unit']?></span></td>  

<script>  
  
               $(document).on('click','.num',function(){  
        var id=$(this).attr('id');  
        var _this=$(this);  
        var new_val=$(this).html();  
        _this.parent().html("<input type='text'class='asdf' value="+new_val+" id="+id+">");  
        var inp=$('.asdf');  
        inp.focus();  
        inp.blur(function(){  
            var old_id=$(this).attr('id');  
            var old_val=$(this).val();  
            //inp.parent().html("<span class="num" id="+old_id+">"+old_val+"</span>");  
            $.get("<?php echo base_url("index.php/good/gai") ?>",{measure_unit:old_val,id:old_id},function(e){  
                if(e==1){  
                    inp.parent().html("<span class="num" id="+old_id+">"+old_val+"</span>");  
                }else{  
                    inp.parent().html("<span class="num" id="+old_id+">"+new_val+"</span>");  
                }  
            })  
        })  
    })  
  
</script>  

public function gai()  
{  
    $data['measure_unit'] = $_GET['measure_unit'];  
    $data['cat_id'] = $_GET['id'];  
    $arr = $this->db->update("category", $data, array('cat_id' => $data['cat_id']));  
    //var_dump($arr);die;  
    if ($arr) {  
        echo 1;  
    } else {  
        echo 0;  
    }  
}