js表格上下移动添加删除

html部分

<div onclick='fn()'>加</div>
    <table width="250" border="1" >
  <tbody id="div">
    <tr>
      <td width="25%">1</td>
      <td width="25%">11</td>
      <td width="25%"><a href="javascript:void(0)" onclick="moveUp(this)">上移</a></td>
      <td width="25%"><a href="javascript:void(0)" onclick="moveDown(this)">下移</a></td>
      <td width="25%"><a href="javascript:void(0)" onclick="shanchu(this)">删除</a></td>
    </tr>
    <tr>
      <td>2</td>
      <td>22</td>
      <td><a href="javascript:void(0)" onclick="moveUp(this)">上移</a></td>
      <td><a href="javascript:void(0)" onclick="moveDown(this)">下移</a></td>
      <td><a href="javascript:void(0)" onclick="shanchu(this)">删除</a></td>
    </tr>
    <tr>
      <td>3</td>
      <td>33</td>
      <td><a href="javascript:void(0)" onclick="moveUp(this)">上移</a></td>
      <td><a href="javascript:void(0)" onclick="moveDown(this)">下移</a></td>
        <td><a href="javascript:void(0)" onclick="shanchu(this)">删除</a></td>
    </tr>
    <tr>
      <td>4</td>
      <td>44</td>
      <td><a href="javascript:void(0)" onclick="moveUp(this)">上移</a></td>
      <td><a href="javascript:void(0)" onclick="moveDown(this)">下移</a></td>
        <td><a href="javascript:void(0)" onclick="shanchu(this)">删除</a></td>
    </tr>
    <tr>
      <td>5</td>
      <td>55</td>
      <td><a href="javascript:void(0)" onclick="moveUp(this)">上移</a></td>
      <td><a href="javascript:void(0)" onclick="moveDown(this)">下移</a></td>
        <td><a href="javascript:void(0)" onclick="shanchu(this)">删除</a></td>
    </tr>
  </tbody>
</table>

css部分

.on{
        background-color: yellow;
    }
    .in{
        background-color:pink;
    }

js部分

//上移
function moveUp(_a){
  var a_tr = _a.parentNode.parentNode;//选点击a的父级td的父级tr
  var a_tr_table=a_tr.parentNode;//tr的父级tbody
  var tr_tr = a_tr.previousSibling;//选择tr的同级前一个节点tr
  console.log(tr_tr.nodeType);
  //nodeType为1代表元素
  while(tr_tr&&tr_tr.nodeType!=1){//while如果不满足条件会一直执行下面的方法
       tr_tr = tr_tr.previousSibling;
  }
  if(tr_tr){
       a_tr_table.insertBefore(a_tr,tr_tr);//insertBefore(a_tr,tr_tr)a_tr要插入的节点,在tr_tr之前
  }
  color();

}
//变色
function color(){
    var element=document.getElementById("div");
    var tr=element.getElementsByTagName('tr');
    for(var i=0;i<tr.length;i++){
        if(i%2==0){
            tr[i].className="on";
        }else{
            tr[i].className="in";
        }
    }
}
color();
//下移
function moveDown(_a){
  var a_tr = _a.parentNode.parentNode;//a的tr
  var tr_tr = a_tr.nextSibling;//a的tr下的tr
  var a_tr_table = a_tr.parentNode;
  console.log(tr_tr.nodeType);
  while(tr_tr && tr_tr.nodeType != 1){
    tr_tr = tr_tr.nextSibling;

  }
  if(tr_tr){
    a_tr_table.insertBefore(tr_tr,a_tr);
  }
  color();

}
//删除
function shanchu(_a){
     var a_tr = _a.parentNode.parentNode;//a的tr
     a_tr.parentNode.removeChild(a_tr);
     color();

}
//添加
var a=1;
var b=2;
function fn(){
            a+=a;
            b+=b;
            var str="<tr><td>"+a+"</td><td>"+b+"</td><td><a href=\"javascript:void(0)\" onclick=\"moveUp(this)\">上移</a></td><td><a href=\"javascript:void(0)\" onclick=\"moveDown(this)\">下移</a></td><td><a href=\"javascript:void(0)\" onclick=\"shanchu(this)\">删除</a></td></tr>";
            var element=document.getElementById("div");
            element.innerHTML+=str;
            color();             
}