<script type="text/javascript">
var statesThruM = ['Alabama', 'Alaska', 'Arizona', 'Arkansas', 'California', 'Colorado', 'Connecticut', 'Delaware', 'Florida', 'Georgia', 'Hawaii', 'Idaho', 'Illinois', 'Indiana', 'Iowa', 'Kansas', 'Kentucky', 'Louisiana', 'Maine', 'Maryland', 'Massachusetts', 'Michigan', 'Minnesota', 'Mississippi', 'Missouri', 'Montana']
function checkMe(str) {
if (statesThruM.join("|").indexOf(str) == -1) {
alert("The state you selected starts with a letter after M");
}
}
</script>
<select onchange="checkMe(this.value)">
<option value='Alabama'>Alabama</option>
<option value='Alaska'>Alaska</option>
<option value='Arizona'>Arizona</option>
<option value='Arkansas'>Arkansas</option>
<option value='California'>California</option>
<option value='Colorado'>Colorado</option>
<option value='Connecticut'>Connecticut</option>
<option value='Delaware'>Delaware</option>
<option value='Florida'>Florida</option>
<option value='Georgia'>Georgia</option>
<option value='Hawaii'>Hawaii</option>
<option value='Idaho'>Idaho</option>
<option value='Illinois'>Illinois</option>
<option value='Indiana'>Indiana</option>
<option value='Iowa'>Iowa</option>
<option value='Kansas'>Kansas</option>
<option value='Kentucky'>Kentucky</option>
<option value='Louisiana'>Louisiana</option>
<option value='Maine'>Maine</option>
<option value='Maryland'>Maryland</option>
<option value='Massachusetts'>Massachusetts</option>
<option value='Michigan'>Michigan</option>
<option value='Minnesota'>Minnesota</option>
<option value='Mississippi'>Mississippi</option>
<option value='Missouri'>Missouri</option>
<option value='Montana'>Montana</option>
<option value='Nebraska'>Nebraska</option>
<option value='Nevada'>Nevada</option>
<option value='New Hampshire'>New Hampshire</option>
<option value='New Jersey'>New Jersey</option>
<option value='New Mexico'>New Mexico</option>
<option value='New York'>New York</option>
<option value='North Carolina'>North Carolina</option>
<option value='North Dakota'>North Dakota</option>
<option value='Ohio'>Ohio</option>
<option value='Oklahoma'>Oklahoma</option>
<option value='Oregon'>Oregon</option>
<option value='Pennsylvania'>Pennsylvania</option>
<option value='Rhode Island'>Rhode Island</option>
<option value='South Carolina'>South Carolina</option>
<option value='South Dakota'>South Dakota</option>
<option value='Tennessee'>Tennessee</option>
<option value='Texas'>Texas</option>
<option value='Utah'>Utah</option>
<option value='Vermont'>Vermont</option>
<option value='Virginia'>Virginia</option>
<option value='Washington'>Washington</option>
<option value='West Virginia'>West Virginia</option>
<option value='Wisconsin'>Wisconsin</option>
<option value='Wyoming'>Wyoming</option>
</select>