How to list categories in a dropdown menu

<?php
    if( $terms = get_terms( array(
        'taxonomy' => 'category', // to make it simple I use default categories
        'orderby' => 'name'
    ) ) ) : 
        // if categories exist, display the dropdown
        echo '<div class="isotope-filter-wrapper">';
            echo '<select name="categoryfilter"><option value="">Select category...</option>';
            foreach ( $terms as $term ) :
                echo '<option value="' . $term->term_id . '">' . $term->name . '</option>'; // ID of the category as an option value
            endforeach;
            echo '</select>';
        echo '</div>';
    endif;  
?>