<div>
<pre>
<select id="colorSelector">
<option value="red">Red</option>
<option value="blue">Blue</option>
<option value="green">Green</option>
</select>
<script>
document.getElementById('colorSelector').addEventListener('change', function(event) {
alert('You selected ' + event.target.value);
});
</script>
</pre>
</div>