关于数据选择的问题

Question

http://lucky.myrice.com/javascriptexam/add_del_Select.htm

Answer 1

<script language=javascript>
function selectMove(oSource,oTarget,cWhich)  //两个选择框选项之间的移动，oSource为源选择框，oTarget为目标选择框，cWhich为提示文字，取值”左“或”右“。
{
  if(!oSource.options.length)
  {
    alert(cWhich+"侧列表中已没有选项可选，无法移动！");
    return;
  }
  if(oSource.selectedIndex==-1)
  {
    alert("操作前您首先应该从"+cWhich+"侧列表中选择一项！");
    return;
  }
  var mySld=new Array();
  for(i=0;i<oSource.options.length;i++)
    if(oSource.options[i].selected)
      mySld[mySld.length++]=i;
  for(i=0;i<mySld.length;i++)
  {
    oTarget.options.length++;
    oTarget.options[oTarget.options.length-1].text=oSource.options[mySld[i]].text;
    oTarget.options[oTarget.options.length-1].value=oSource.options[mySld[i]].value;
  }
  for(i=0;i<mySld.length;i++)
  {
    for(j=mySld[i]-i;j<oSource.options.length-1;j++)
    {
      oSource.options[j].text=oSource.options[j+1].text;
      oSource.options[j].value=oSource.options[j+1].value;
    }
    oSource.options.length--;
  }
}function moveAll(oSource,oTarget)
{
  var n=oTarget.options.length;
  oTarget.options.length=n+oSource.options.length;
  for(i=n;i<oTarget.options.length;i++)
  {
    oTarget.options[i].text=oSource.options[i-n].text;
    oTarget.options[i].value=oSource.options[i-n].text.value;
  }
  oSource.options.length=0;
}
</script><form name=form1>
<table class=setrole_tab>
  <tr>
    <td>
      未加入角色<br>
      <select size=15 style="width:150px;" name=notadded_role ondblclick="selectMove(document.form1.notadded_role,document.form1.added_role,'左')" multiple>
        <option>aaaaaaaa</option>
        <option>bbbbbbbb</option>
        <option>cccccccc</option>
        <option>dddddddd</option>
      </select>
    </td>
    <td>
      <a href="javascript:moveAll(document.form1.notadded_role,document.form1.added_role);">全部右移</a><br>
      <a href="javascript:selectMove(document.form1.notadded_role,document.form1.added_role,'左')"><img src=images/move_right.gif alt=右移></a><br>
      <a href="javascript:selectMove(document.form1.added_role,document.form1.notadded_role,'右')"><img src=images/move_left.gif alt=左移></a><br>
      <a href="javascript:moveAll(document.form1.added_role,document.form1.notadded_role);">全部左移</a>
    </td>
    <td>
      已加入角色<br>
      <select size=15 style="width:150px;" name=added_role ondblclick="selectMove(document.form1.added_role,document.form1.notadded_role,'右')" multiple>
        <option>eeeeeeee</option>
        <option>ffffffff</option>
        <option>gggggggg</option>
      </select>
    </td>
  </tr>
</table>
</form>
提示：按住Ctrl键可进行多选