js获取select值和改变select值

 js获取select值

<script language="javascript">
function selectInput(choose){
    alert(choose.value);
    alert(choose.options[choose.selectedIndex].text);
}
</script>
<select name="Month" onchange="selectInput(this)">
    <option  value="01">January</option>
    <option  value="02">February</option>
    <option  value="03">March</option>
    <option  value="04">April</option>
    <option  value="05">May</option>
    <option  value="06">June</option>
    <option  value="07">July</option>
    <option  value="08" selected="selected">August</option>
    <option  value="09">September</option>
    <option  value="10">October</option>
    <option  value="11">November</option>
    <option  value="12">December</option>
</select>

 

js改变select值

 

<script>
function fid_check(){
    alert('不能选择大分类，请选择黑色字体的小分类');
    document.getElementById('isempty').selected=true;
}
</script>

<select>
<option id="isempty" value="">--请选择--</option>
<option value="大分类">大分类</option>
<option value="小分类">小分类</option>
</select>