Just copy and paste javascript code given below and pass the parameter dropdownlist id, you can customize alert validation error message according to requirement.
Asp.net server control code :
<asp:DropDownList runat="server"
ID="ddl">
<asp:ListItem Text="-Select-" Value="0"></asp:ListItem>
<asp:ListItem Text="One" Value="1"></asp:ListItem>
<asp:ListItem Text="Two" Value="2"></asp:ListItem>
<asp:ListItem Text="Three" Value="3"></asp:ListItem>
</asp:DropDownList>
Rendered code in html (client side code) :
<select id="ddl">
<option value="0">-Select-</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
</select>
Validate dropdownlist by value field in javascript
function
Dropdown_Validation(ddlId) {
var empty =
document.getElementById(ddlId).value;
if (empty == "0")
{
alert('Please select an item');
return false;
}
return true;
return true;
}
Validating dropdown list by text field in javascript
function Dropdown_Validation(ddlId) {
var ddl = document.getElementById(ddlId);
var ddlText = ddl.options[ddl.selectedIndex].text;
if (ddlText == "-Select-") {
alert('Please select an item');
return false;
}
return true;
return true;
}
Validate dropdownlist by selectedIndex property in javascript
function Dropdown_Validation(ddlId) {
var ddl = document.getElementById(ddlId);
if (ddl.selectedIndex == 0 ) {
alert('Please select an item');
return false;
}
return true;
return true;
}
