example of jquery select option by value

Example 1: jquery get selected option value

var selectedOptionText = $('#mySelectID').find(":selected").text();//selected option text
var selectedOptionVal = $('#mySelectID').find(":selected").val();//selected option value

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(); 
        }
    });
});