select下拉域，左右增加，和移除
//增加function addOption(){var selectconfig=form.selectconfig.value;//获取显示值var selectconfigvalue=document.getElementById("selectconfig").options[document.getElementById("selectconfig").selectedIndex].text;var selectnews=document.getElementById("selectnew");if (selectconfig=="") { alert ("请选择添加项"); return false;}var i=0;var b=true;for(var j=0;j<selectnews.options.length;j++){ if (selectconfig==selectnews.options[j].text){ b=false; } } if(b){ i++; selectnews.options.add(new Option(selectconfigvalue,selectconfig),i); } }//删除function delOption(){var selectnews=form.selectnew.value;if (selectnews=="") { alert ("请选择删除项"); return false;}var length2=document.getElementById("selectnew");length2.options.remove(length2.options.selectedIndex);}<table width="770" align="center"><tr><td>字段列表<br/><SELECT size=10 name="selectconfig" id="selectconfig" style="width=200px"><OPTION value="title">标题</OPTION><OPTION value="message">描述</OPTION></SELECT></td><td><input type="button" name="" value="添加--->" onclick="addOption();"><br/><br/><input type="button" name="" value="<---移除" onclick="delOption();"></td><td>已选列表<br/><SELECT size=10 name="selectnew" id="selectnew" style="width=200px"></SELECT></td></tr></table>