Beispiel für das dynamische Hinzufügen und Löschen von linken und rechten Dropdown-Feldern mithilfe von JavaScript

 functionmoveRight()

 {

   //获取左边select元素节点

   varleftSelectNode = 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

   varwaitSelection = leftSelectNode.options[leftSelectNode.selectedIndex];

   //获取右边的selec元素节点并加入

   varrightSelectNode = document.getElementById("right");

   //右边新增一个节点

   rightSelectNode.appendChild(waitSelection);

 }

 functionmoveAllright()

 {//获取select对象

   varleftSelectNode = document.getElementById("left");

   varrightSelectNode = document.getElementById("right");

   varoptionsNodes = leftSelectNode.options;

   varlength = optionsNodes.length;

   for(vari = 0; i

   {

     rightSelectNode.appendChild(optionsNodes[0]);

   }

 }

 functionmoveLeft()

 {

   //获取左边的select对象

  varrightSelectNode = 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

   varwaitMoveNode = rightSelectNode.options[rightSelectNode.selectedIndex];

   //获取左边的select对象

   varleftSelectNode = document.getElementById("left");

   //左边的select对象加入节点

   leftSelectNode.appendChild(waitMoveNode);

 }

 functionmoveAllLeft()

 {

   //获取右边的select对象

   varrightSelectNode = document.getElementById("right");

   varleftSelectNode = document.getElementById("left");

   varlength = rightSelectNode.options.length;

   //遍历其option选项并加入到左边的select中

   for(vari = 0; i

   {

     leftSelectNode.appendChild(rightSelectNode.options[0]);

   }

 }