JavaScript控制两个列表框listbox左右交换数据

这个功能我们经常用到，将左边列表框的元素移动到右边，或者将右边列表框的元素移动到左边，可以一次性全部移动

function listbox_moveacross(sourceID, destID) {
    var src = document.getElementById(sourceID);
    var dest = document.getElementById(destID);
  
    for(var count=0; count < src.options.length; count++) {
  
        if(src.options[count].selected == true) {
                var option = src.options[count];
  
                var newOption = document.createElement("option");
                newOption.value = option.value;
                newOption.text = option.text;
                newOption.selected = true;
                try {
                         dest.add(newOption, null); //Standard
                         src.remove(count, null);
                 }catch(error) {
                         dest.add(newOption); // IE only
                         src.remove(count);
                 }
                count--;
        }
    }
}
// http://www.75271.com
//..

listbox_moveacross('countryList', 'selectedCountryList');

下面是像是的演示效果代码，可以直接在浏览器内执行

Click below buttons to move selected options right or left.<br>
<table>
<tbody><tr>
    <td>
<select id="sourceSelect" size="10" multiple="">
	<option value="a">Afghanistan</option>
	<option value="b">Bahamas</option>
	<option value="c">Barbados</option>
	<option value="d">Belgium</option>
	<option value="e">Bhutan</option>
	<option value="f">China</option>
	<option value="g">Croatia</option>
	<option value="h">Denmark</option>
	<option value="i">France</option>
</select>
    </td>
    <td>
        <button onclick="listboxMoveacross('sourceSelect', 'destSelect');">>></button>  <br>
        <button onclick="listboxMoveacross('destSelect', 'sourceSelect');"><<</button>
    </td>
    <td>
<select id="destSelect" size="10" multiple="">
	<option value="a">Afghanistan</option>
	<option value="b">Bahamas</option>
	<option value="c">Barbados</option>
	<option value="d">Belgium</option>
	<option value="e">Bhutan</option>
	<option value="f">China</option>
	<option value="g">Croatia</option>
	<option value="h">Denmark</option>
	<option value="i">France</option>
</select>
    </td>
</tr>
</tbody></table>

    <script>
function listboxMoveacross(sourceID, destID) {
    var src = document.getElementById(sourceID);
    var dest = document.getElementById(destID);

    for(var count=0; count < src.options.length; count++) {

        if(src.options[count].selected == true) {
                var option = src.options[count];

                var newOption = document.createElement("option");
                newOption.value = option.value;
                newOption.text = option.text;
                newOption.selected = true;
                try {
                         dest.add(newOption, null); //Standard
                         src.remove(count, null);
                 }catch(error) {
                         dest.add(newOption); // IE only
                         src.remove(count);
                 }
                count--;
        }
    }
}
</script>