detect when a value is selected in dropdown jquery code example

Example 1: jqury get selected option

<select id="myselect">
    <option value="1">Mr</option>
    <option value="2">Mrs</option>
    <option value="3">Ms</option>
    <option value="4">Dr</option>
    <option value="5">Prof</option>
</select>

<script>
$( "#myselect option:selected" ).val();
</script>

Example 2: jquery dropdown selected value show field

jQuery(document).ready(function() {
    jQuery("#carm3").change(function() {
        if (jQuery(this).val() === 'other'){ 
            jQuery('input[name=other_interest]').show();   
        } else {
            jQuery('input[name=other_interest]').hide(); 
        }
    });
});