Try the following lines of code-
$('select').on('change', function() {
alert( this.value );
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js">
</script> <select>
<option value="1">One</option>
<option value="2">Two</option>
</select>
You can also reference with onchange event-
function getval(sel)
{
alert(sel.value);
}
<select onchange="getval(this);">
<option value="1">One</option>
<option value="2">Two</option>
</select>