I want to carry out form validation for drop down lists. My website has 10 drop down lists. I want an alert message to be displayed whenever the user selects a blank field from a drop down list. One of the sample drop down list runs as follows:

<strong>Groom's Current Profession</strong>
    <form name="profession">
        <select name="groomprofession" onchange="formValues('profession', 'groomprofession')">
            <option value="c1"></option>
            <option value="c2">Doctor</option>
            <option value="c3">Engineer</option>
            <option value="c4">Lawyer</option>
            <option value="c5">CA</option>
            <option value="c6">Family Business</option>
            <option value="c7">Teacher</option>
            <option value="c8">Journalist</option>            
            <option value="c9">Business Analyst</option> 
How can I include a function that displays an alert message whenever a user selects a blank option from the drop down list? Thanks!