Authenticate Dropdown Field For Free

The easiest way to achieve this is by including an <option> element in the select list HTML as shown below. value attribute of the Please Select option element is set to an empty string. We are also using asp-validation-for tag helper to display the validation error.

And here is my javascript function to validate the dropdown. <script type="text/javascript"> function validate() { if (document.getElementById("<%=ddl_country.ClientID%>").value == "--Select--") { alert('!!!!!! ... document.getElementById("<%=ddl_country.ClientID%>").focus(); return false; } return true;

To make a select mandatory with HTML, use the required attribute. With the required attribute, the user must select a value before submitting the form; if the user refuses to select a value, then the form won't submit.

The default HTML code for the Validation Select widget, usually inside of a form, is made up of a container span tag that surrounds the select tag of the text area. The HTML code for the Validation Select widget also includes script tags in the head of the document and after the widget's HTML code.

Attributes of the Select Tag multiple: This attribute lets the user select multiple options from the dropdown menu. required: This is typically used for validation. With it, the form won't submit unless a user selects at least one option from the dropdown.

There are two methods of getting the value of the selected option. You can either select text or find the position of it in a drop-down list by using the option:selected attribute or the val() method in jQuery.

And here is my javascript function to validate the dropdown. <script type="text/javascript"> function validate() { if (document.getElementById("<%=ddl_country.ClientID%>").value == "--Select--") { alert('!!!!!! ... document.getElementById("<%=ddl_country.ClientID%>").focus(); return false; } return true;