<asp:DropDownList id="ddlyear" runat="server" >
<asp:ListItem selected hidden>Experience</asp:ListItem>
<asp:ListItem>Fresher</asp:ListItem>
<asp:ListItem>1</asp:ListItem>
<asp:ListItem>2</asp:ListItem>
<asp:ListItem>3</asp:ListItem>
</asp:DropDownList>
selected
属性将其设置为默认值,而hidden
属性防止它在展开列表中可见。
这是可能最简单的方法。
仅使用HTML是无法实现此功能的,您需要使用Html + jQuery。
<asp:DropDownList ID="ddlyear" runat="server">
<asp:ListItem>Experience</asp:ListItem>
<asp:ListItem>Fresher</asp:ListItem>
<asp:ListItem>1</asp:ListItem>
<asp:ListItem>2</asp:ListItem>
<asp:ListItem>3</asp:ListItem>
</asp:DropDownList>
<script>
var isChanged = false;
$(function () {
$('#ddlyear').focusin(function () {
if (!isChanged) {
// this removes the first item which is your placeholder if it is never changed
$(this).find('option:first').remove();
}
});
$('#ddlyear').change(function () {
// this marks the selection to have changed
isChanged = true;
});
$('#ddlyear').focusout(function () {
if (!isChanged) {
// if the control loses focus and there is no change in selection, return the first item
$(this).prepend('<option selected="selected" value="0">Experience</option>');
}
});
});
</script>
<head runat="server">
<title></title>
// Sample only, you can place it in any location or use any version
<script src="../scripts/jquery-2.2.2.min.js"></script>
</head>
@amit
兄弟,试试这个....
<select placeholder="select your beverage">
<option value="" default="" selected="">select your beverage</option>
<option value="tea">Tea</option>
<option value="coffee">Coffee</option>
<option value="soda">Soda</option>
</select>
<asp:DropDownList id="ddlyear" runat="server">
<asp:ListItem Value="">Select</asp:ListItem>
<asp:ListItem Value="Experience">Experience</asp:ListItem>
<asp:ListItem Value="Fresher">Fresher</asp:ListItem>
<asp:ListItem Value="1">1</asp:ListItem>
<asp:ListItem Value="2">2</asp:ListItem>
<asp:ListItem Value="3">3</asp:ListItem>
</asp:DropDownList>