validation in javascript using asp.net control in c# for dropdown list

Question

1.00/5 (1 vote)

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C#3.0

C#

can you tell how to implement javascript validation in asp.net controls for c# language for dropdown list.

Posted 23-Feb-12 17:21pm

meeraradha

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4 solutions

Solution 1

Here is the sample code to validate Email field from asp.net dropdownlist box. Javascript as:

JavaScript

<script language="javascript" type="text/javascript">
function validateDropList()
{
      if(document.getElementById("<%=drop1.SelectedIndex %>").value=="")
      {
                 alert("Email id can not be blank");
                document.getElementById("<%=drop1.SelectedIndex %>").focus();
                return false;
      }
}
</script>

User Interface code as:

ASP.NET

<asp:dropdownlist id="drop1" runat="server" xmlns:asp="#unknown">
... 
</asp:dropdownlist>

Code behind as:

C#

drop1.Attributes.Add("onselectedindexchanged", "return validateDropList()")

Hope, it clarifies.

Posted 23-Feb-12 17:32pm

Ganesan Senthilvel

Comments

meeraradha 23-Feb-12 23:46pm

please dont give an example with email validation.i need just for an simple field like text box,radio button or dropdown.

label contains a name it should validate the details entering in the textbox like that.the feild should not be empty and it should contain with limited characters and no numeric should be allowed.

Solution 2

Hello use the onChange attribute to write a javascript.

this code might help you:

XML

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript">
        function displaySelected() {
            var x = document.getElementById('<%=ddlFruits.ClientID%>');
            var txt = "Selected option: " + x.value;
            alert(txt);
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="ddlFruits" runat="server" onChange="javascript:displaySelected();">
            <asp:ListItem Text="Apple" />
            <asp:ListItem Text="Orange" />
        </asp:DropDownList>
    </div>
    </form>
</body>
</html>

Posted 23-Feb-12 17:50pm

Ankit Kumar Gupta

Solution 3

if nothing is selected in dropdownlist it should display an error message.

Posted 23-Feb-12 17:55pm

meeraradha

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Ankit Kumar Gupta · Accepted Answer · 2012-02-23T18:19:00

Hi, something has to be selected. so you can add a default value and use it.

Sample Code:

XML

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript">
        function displaySelected() {
            var x = document.getElementById('<%=ddlFruits.ClientID%>');
            var txt;
            if (x.value == 'Select') {
                txt = "Please select any fruit";
            }
            else {
                txt = "Selected option: " + x.value;
            }
            alert(txt);
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:DropDownList ID="ddlFruits" runat="server" onChange="javascript:displaySelected();">
            <asp:ListItem Text="Select" Selected="True" />
            <asp:ListItem Text="Apple" />
            <asp:ListItem Text="Orange" />
        </asp:DropDownList>
    </div>
    </form>
</body>
</html>