Example of how to conditionally hide/show a text question based on a drop down question value. Works with Event Espresso 4

functions.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

// In this example the *text* question div class is .ee-reg-qstn-13-input-dv
// and the *dropdown* question input class is .ee-reg-qstn-12

function ee_custom_show_question_conditionally() {
    wp_add_inline_script( 
        'ee_form_section_validation',
        'jQuery( document ).ready(function($) {
            var text = $(".ee-reg-qstn-13-input-dv");
            $(text).hide();
            $(".ee-reg-qstn-12").change(function() {
                $(this).val() == "other" ?
                $(text).show() :
                $(text).hide();
            });
        });'
    );
}
add_action(
    'wp_enqueue_scripts',
    'ee_custom_show_question_conditionally',
    11
);