In your comment, you ask for a solution without JavaScript, but that's not possible. So here's a solution that does use JavaScript.
- Set the "value" attribute on your first "option" to
"none"
:
<option disabled="disabled" selected="selected" value="none">Severity ▼</option>
- In your validation code, check that the selected value is not equal to
"none"
:
if (document.getElementById("DropDownSeverity").value === "none") {
alert("Please select a severity.");
return;
}
Note that people can use your browser developer tools to change the value of the element to something else to circumvent the validation.
If you send this value to a server, make sure to validate it on the server-side as well. If your application is purely client-side, no need to worry about it.