/*
  * 删除数组元素:Array.removeArr(index)
  */
  Array.prototype.removeArr = function (index) {
    if (isNaN(index) || index>= this.length) { return false; }
    this.splice(index, 1);
  }
  /*
  * 插入数组元素:Array.insertArr(dx)
  */
  Array.prototype.insertArr = function (index, item) {
    this.splice(index, 0, item);
  };

if (tag == 2) { //上移
      if (targeitemindex == 0) return; //顶部
      rows.removeArr(targeitemindex); //移除指定对象，原对象长度减少一个
      rows.insertArr(targeitemindex - 1, targetitem);
    } else if (tag == 3) { //下移
      if (targeitemindex == len - 1) return; //底部
      rows.removeArr(targeitemindex); //移除指定对象，原对象长度减少一个
      rows.insertArr(targeitemindex + 1, targetitem);
    }

arrayObject.splice(index,howmany,item1,.....,itemX)