jQuery는 선택 취소 selected_jquery 설정의 텍스트와 값을 가져옵니다.

$("#ddlregtype").find("option:selected").text();

$("#ddlregtype ").val();

$("#ddlregtype ").get(0).selectedindex;

$("#ddlregtype ").get(0).selectedindex=index;//index为索引值

$("#ddlregtype ").attr("value","normal“);
$("#ddlregtype ").val("normal");
$("#ddlregtype ").get(0).value = value;

var count=$("#ddlregtype option").length;
for(var i=0;i<count;i++)
{ if($("#ddlregtype ").get(0).options[i].text == text)
{
$("#ddlregtype ").get(0).options[i].selected = true;
break;
}
}
$("#select_id option[text='jquery']").attr("selected", true);

$("#select_id").append("<option value='value'>text</option>"); //添加一项option
$("#select_id").prepend("<option value='0'>请选择</option>"); //在前面插入一项option
$("#select_id option:last").remove(); //删除索引值最大的option
$("#select_id option[index='0']").remove();//删除索引值为0的option
$("#select_id option[value='3']").remove(); //删除值为3的option
$("#select_id option[text='4']").remove(); //删除text值为4的option

$("#ddlregtype ").empty();

//获取所有属性值 var item = $("#select1").val();
$(function(){
$('#select1').each( //获得select1的所有值
function(){
$('button').click(function(){
alert($('#select2').val()); //获得select2中的select1值
});
});
})
</script>

$(function(){
$('#select2').each( //获得select1的所有值，因为前面讲选项从左边添加到右边，jquery其实并没有真正将值从左边传到右边。
function(){
$('button').click(function(){
alert($(this).val()); //获得select2中的select1值
});
});
})

<div class="centent">
<select multiple="multiple" id="select1" name="dd" style="width:100px;height:160px;">
<option value="1">选项1</option>
<option value="2">选项2</option>
<option value="3">选项3</option>
<option value="4">选项4</option>
<option value="5">选项5</option>
<option value="6">选项6</option>
<option value="7">选项7</option>
</select>
<div>
<span id="add" >选中添加到右边>></span>
<span id="add_all" >全部添加到右边>></span>
</div>
</div>
<div class="centent">
<select multiple="multiple" id="select2" name="sel" style="width: 100px;height:160px;">
</select>
<div>
<span id="remove"><<选中删除到左边</span>
<span id="remove_all"><<全部删除到左边</span>
</div>
</div>

//绑定ClassLevel1单击事件
$("#ClassLevel1").change(function () {
var id = $("#ClassLevel1").val();
var level2 = $("#ClassLevel2");
level2.empty();
$("#ClassLevel3").hide();
$.ajax({
url: "./askCommon.ashx?action=getclasslevel&pid=" + id,
data: { "type": "ajax" },
datatype: "json",
type: "get",
success: function (data) {
var json = eval_r(data);
for (var ind in json) {
level2.append($("<option value='" + json[ind].id + "'>" + json[ind].typename + "</option>"));
}

}
});
})