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JavaScript sample code to implement dynamic addition and deletion of left and right drop-down boxes

黄舟Original: 2017-03-22 14:31:481343browse

This article mainly introducesJavaScriptAn example of dynamic addition and deletion of left and right drop-down boxes. The drop-down boxes can be deleted and added. It is of great practical value. Friends in need can refer to it.

Select the option in the drop-down box to move left and right

Effect:

1. Html part code

<body>
<table align="center">
  <tr>
    <td ><select size="15" id="left" >
      <option>左1</option>
      <option>左2</option>
      <option>左3</option>
      <option>左4</option>
      <option>左5</option>
      <option>左6</option>
      <option>左7</option>
      <option>左8</option>
      <option>左9</option>
      <option>左10</option>
    </select></td>

    <td>
      <input type="button" value="MoveRight" onclick="moveRight()"><br>
      <input type="button" value="MoveAllRight" onclick="moveAllright()"/><br>
      <input type="button" value="MoveLeft" onclick="moveLeft()"><br>
      <input type="button" value="MoveAllLeft" onclick="moveAllLeft()"><br>
    </td>


    <td>
      <select size="15" id="right">
        <option>右1</option>
        <option>右2</option>
        <option>右3</option>
        <option>右4</option>
        <option>右5</option>
        <option>右6</option>
        <option>右7</option>
      </select>
    </td>

    <td></td>
  </tr>

  </table>

</body>

2. The JavaScript script code is as follows:

  <script type="text/javascript">
   function moveRight()
   {
     //获取左边select元素节点
     var leftSelectNode = document.getElementById("left");
     //获取子元素节点数组
     //如果选定的索引号为-1,则提示用户
     if (leftSelectNode.selectedIndex == -1)
     {
       alert("请选定需要移动的选项");
       return;
     }
     //获取待移动的选项
     var waitSelection = leftSelectNode.options[leftSelectNode.selectedIndex];
     //获取右边的selec元素节点并加入
     var rightSelectNode = document.getElementById("right");
     //右边新增一个节点
     rightSelectNode.appendChild(waitSelection);

   }

   function moveAllright()
   {//获取select对象
     var leftSelectNode = document.getElementById("left");
     var rightSelectNode = document.getElementById("right");

     var optionsNodes = leftSelectNode.options;

     var length = optionsNodes.length;
     for (var i = 0; i < length; i++)
     {
       rightSelectNode.appendChild(optionsNodes[0]);
     }
   }

   function moveLeft()
   {
     //获取左边的select对象
    var rightSelectNode = document.getElementById("right");
    //没有选中则提示
     if (rightSelectNode.selectedIndex == -1)
     {
       alert("请选择一个选项");
       return;
     }
     //获取待移动的选项
     var waitMoveNode = rightSelectNode.options[rightSelectNode.selectedIndex];
     //获取左边的select对象
     var leftSelectNode = document.getElementById("left");

     //左边的select对象加入节点
     leftSelectNode.appendChild(waitMoveNode);

   }
   function moveAllLeft()
   {
     //获取右边的select对象
     var rightSelectNode = document.getElementById("right");
     var leftSelectNode = document.getElementById("left");

     var length = rightSelectNode.options.length;

     //遍历其option选项并加入到左边的select中
     for (var i = 0; i < length; i++)
     {
       leftSelectNode.appendChild(rightSelectNode.options[0]);
     }
   }

  </script>

3. The simple CSS code is as follows:

  <style>
    select, td
    {
      font:20px/40px &#39;宋体&#39;;
    }
    option {width: 100px;
      font:20px/40px &#39;宋体&#39;;
    }
    input {
      padding: 3px;
      font:20px/40px &#39;宋体&#39;;
      text-align: center;
      width: 130px;
      height: 40px;
      background-color: orange;
    }
  </style>

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