JS获取下拉列表选中项的值和文本

function getSelectedValue(name){
var obj=document.getElementById(name);
return obj.value;      //如此简单，直接用其对象的value属性便可获取到
}

<select Id="select">
<option>1</option>
<option selected="selected">2</option>
<option>3</option>
</select>

<script language="javascript" type="text/javascript">
var ById = document.getElementById("Select")
alert(ById.options[ById.selectedIndex].text)
</script>

<select id="select1" onChange="abc()">
<option value="1">看书</option>
<option value="2">体育</option>
</select>
<script type="text/javascript">
function abc(){
var obj =document.getElementById("select1");
alert(obj.options[obj.selectedIndex].text);
}
</script>

$("#select option[selected]").text();

//select和option之间有空格，option为select的子元素

$("#select option:selected").text();

$("#select").val();//取值
$("#select").val("value");//设置,如果select中有值为value的选项,该选项就会被选中,如果不存在,则select不做