那么skyover请帮个忙吧

select2.options[select2.selectedIndex]=nullORselect2.remove(select2.selectedIndex)

解决方案 »

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<html>
<head>
<script>
  function addOption()
  {
var the_option= new Option(select1.value,select1.value);
select2.add(the_option);
select2.selectedIndex = select2.options.length-1
  }
function delOption()
  {
select2.selectedIndex = select2.options.length + 1
select2.options = ""
  }function delOpetion2() {
select2.options.remove(select2.selectedIndex);
}
</script>
</head>
<body>
<select name=select1 multiple>
<option value='aaaaa'>aaaaa</option>
<option value='bbbbb'>bbbbb</option>
<option value='ccccc'>ccccc</option>
<option value='ddddd'>ddddd</option>
<option value='eeeee'>eeeee</option>
</select>
<input type=button value="==>" onclick="addOption()">
<input type=button value="<==" onclick="delOpetion2()">
<select name=select2  multiple></select>
</body>
</html>
<html>
<head>
<script>
  function addOption()
  {
var the_option= new Option(select1.value,select1.value);
select2.add(the_option);
select2.selectedIndex = select2.options.length-1
  }
function delOption()
  {
var si=select2.selectedIndex
var oOption=select2.options[si];
select2.removeChild(oOption)
  }
</script>
</head>
<body>
<select name=select1 multiple>
<option value='aaaaa'>aaaaa</option>
<option value='bbbbb'>bbbbb</option>
<option value='ccccc'>ccccc</option>
<option value='ddddd'>ddddd</option>
<option value='eeeee'>eeeee</option>
</select>
<input type=button value="==>" onclick="addOption()">
<input type=button value="<==" onclick="delOption()">
<select name=select2  multiple></select>
</body>
</html>
<html>
<head>
<script>
  function addOption()
  {
var the_option= new Option(select1.value,select1.value);
select2.add(the_option);
select2.selectedIndex = select2.options.length-1
  }
function delOption()
  {
select2.selectedIndex = select2.options.length + 1
select2.options = ""
  }function delOpetion2() {
   try{
select2.options.remove(select2.selectedIndex);
}
catch(x){alert('请先选择再删除')}
}
</script>
</head>
<body>
<select name=select1 multiple>
<option value='aaaaa'>aaaaa</option>
<option value='bbbbb'>bbbbb</option>
<option value='ccccc'>ccccc</option>
<option value='ddddd'>ddddd</option>
<option value='eeeee'>eeeee</option>
</select>
<input type=button value="==>" onclick="addOption()">
<input type=button value="<==" onclick="delOpetion2()">
<select name=select2  multiple></select>
</body>
</html>