利用js给select动态添加option并选中该option
<script>function addOptionToSelect(){ var slt=document.getElementById("slt"); var objOption=document.createElement("OPTION"); objOption.value='6'; objOption.text='content'; slt.add(objOption); alert(slt.options.length); slt.options[slt.options.length-1].selected='selected';}function getvalue(){ var slt=document.getElementById("slt"); alert(slt.value);}</script><input type="button" value="add option" onclick="addOptionToSelect()"><br><select id="slt"><option value='1'>aaaa</option><option value='2'>bbbb</option><option value='3'>cccc</option><option value='4'>dddd</option><option value='5'>eeee</option></select><br><input type="button" value="get value" onclick="getvalue()">?