Introduction: In this article I am going to explain with example How to
reset or clear asp.net dropdownlist or html dropdown selected value to set it back to its initial/default
state using jquery.
In previous articles I explained JQuery to enable disable all html or asp.net controls placed inside div based on dropdownlist selected value and Reset all asp.net controls on page at once and jQuery AJAX JSON example in Asp.net to insert data into sql server database without postback and Auto resize textarea or Asp.net multiline textbox based on content using javascript
Description: We all know that in
asp.net we can clear dropdownlist using the server side code i.e. DropDownList1.ClearSelection()
method. Same functionality can be achieved at client side using jquery very easily. There
are a number of ways to reset dropdown list back to default state. I am going
to share some of them through this short article.
First
Method
Set the value of DropDownList to 0 which is the first item in our list.
$('#ddlMonths').val('0');
If
the value of first item in dropdownlist is 1:
$('#ddlMonths').val('1');
If the value of first item in dropdownlist is -1 :
$('#ddlMonths').val('-1');
If the value of first item in dropdownlist is “—Select--” :
$('#ddlMonths').val('--Select--');
Second
Method
Set the very first
item of the list as selected.
If
using 1.6 or higher version of jquery
$('#ddlMonths').find('option:first').prop('selected', 'selected');
Or
$('#ddlMonths').find('option:first').prop('selected', true);
$('#ddlMonths').find('option:first').prop('selected', true);
If
using lower than 1.6 version of jquery
$('#ddlMonths').find('option:first').attr('selected', 'selected');
Or
$('#ddlMonths').find('option:first').attr('selected', true);
$('#ddlMonths').find('option:first').attr('selected', true);
Third
Method
Set the very first
item of the list as selected.
If
using 1.6 or higher version of jquery
$('#ddlMonths option:eq(0)').prop('selected', 'selected');
Or
$('#ddlMonths option:eq(0)').prop('selected', true);
$('#ddlMonths option:eq(0)').prop('selected', true);
If using lower than 1.6 version of jquery
$('#ddlMonths option:eq(0)').attr('selected', 'selected');
Or
$('#ddlMonths option:eq(0)').attr('selected', true);
$('#ddlMonths option:eq(0)').attr('selected', true);
Fourth
Method
Set SelectedIndex of DropDownList to 0, which is the first item in our DropDownList
$('#ddlMonths').get(0).selectedIndex = 0;
$('#ddlMonths').get(0).selectedIndex = 0;
Implementation: Let’s check these
methods by implementing it.
HTML Source Code:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Reset HTML dropdown or Asp.Net
DropDownList using jQuery </title>
<script
src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script
type="text/javascript">
function ResetDropDownList() {
$('#ddlMonths').val('0');
//or you
can uncomment any of the method commented below. All works fine.
//$('#ddlMonths').val('--Select--');
//$('#ddlMonths').find('option:first').prop('selected',
'selected');
//$('#ddlMonths').find('option:first').prop('selected',
true);
//$('#ddlMonths').find('option:first').attr('selected',
'selected');
//$('#ddlMonths').find('option:first').attr('selected',
true);
//$('#ddlMonths
option:eq(0)').prop('selected', 'selected');
//$('#ddlMonths
option:eq(0)').prop('selected', true);
//$('#ddlMonths
option:eq(0)').attr('selected', 'selected');
//$('#ddlMonths
option:eq(0)').attr('selected', true);
//$('#ddlMonths').get(0).selectedIndex
= 0;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<fieldset
style="width:350px;">
<legend>Reset HTML dropdown or Asp.Net
DropDownList</legend>
Select Month:
<asp:DropDownList ID="ddlMonths" runat="server" Width="180px">
<asp:ListItem
Value="0" Text="--Select--"></asp:ListItem>
<asp:ListItem
Value="1" Text="January"></asp:ListItem>
<asp:ListItem
Value="2" Text="february"></asp:ListItem>
<asp:ListItem
Value="3" Text="March"></asp:ListItem>
<asp:ListItem
Value="4" Text="April"></asp:ListItem>
<asp:ListItem
Value="5" Text="May"></asp:ListItem>
<asp:ListItem
Value="6" Text="June"></asp:ListItem>
<asp:ListItem
Value="7" Text="July"></asp:ListItem>
<asp:ListItem
Value="8" Text="August"></asp:ListItem>
<asp:ListItem
Value="9" Text="September"></asp:ListItem>
<asp:ListItem
Value="10" Text="October"></asp:ListItem>
<asp:ListItem
Value="11" Text="November"></asp:ListItem>
<asp:ListItem
Value="12" Text="December"></asp:ListItem>
</asp:DropDownList>
<asp:Button
ID="btnReset" runat="server" OnClientClick="ResetDropDownList()" Text="Reset" />
<%--If you want HTML dropdown instead of
Asp.Net DropDownList then comment out
the above
dropdownlist and button control and uncomment below section--%>
<%--
Select Month:
<select
id="ddlMonths">
<option
value="0">--Select--</option>
<option
value="1">January</option>
<option
value="2">february</option>
<option
value="3">March</option>
<option
value="4">April</option>
<option
value="5">May</option>
<option
value="6">June</option>
<option
value="7">July</option>
<option
value="8">August</option>
<option
value="9">September</option>
<option
value="10">October</option>
<option
value="11">November</option>
<option
value="12">December</option>
</select>
<input
type="button" id="btnReset"
onclick="ResetDropDownList()" value="Reset" />--%>
</fieldset>
</div>
</form>
</body>
</html>
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