WordPress taxonomy dropdowns - if too long (default is to show all taxonomies)

taxonomy-dropdowns.js

jQuery(document).ready(function($) {

    /*
     * For Taxonomy dropdowns in Post meta
     */
    $( '.cat-links .jkl-tax-switch, .tags-links .jkl-tax-switch' ).click( function( e ) {
          e.preventDefault();
          if( $( this ).next( 'ul' ).hasClass( 'childopen' ) ) {
              $( this ).next( 'ul' ).removeClass( 'childopen' );
          } else {
              $( this ).next( 'ul' ).addClass( 'childopen' );
          }
    });
    $( '.cat-links .jkl-tax-switch, .tags-links .jkl-tax-switch' ).hover( function ( e ) {
          e.preventDefault();
          if( $( '.entry-meta .cat-links ul' ).hasClass( 'childopen' ) ) {
              $( '.entry-meta .cat-links ul' ).removeClass( 'childopen' );
          } else {
              $( '.entry-meta .cat-links ul' ).addClass( 'childopen' );
          }
    });

});

taxonomy-dropdowns.php

<?php
/**
 * Better Categories (displays them as a dropdown menu)
 */
function jkl_better_taxonomy_listing( $taxonomy_type, $length = -1 ) {
    if ( 'post' === get_post_type() ) {
        
        // If the taxonomy type is 'category'
        if( 'category' === $taxonomy_type ) {
            
            /* translators: used between list items <li> */
            $list = get_the_category_list( __( '</li><li>', 'jkl' ) );
            $search = '</a>';
            $separator = ', ';
            $test = $list && jkl_categorized_blog();
            $class = 'cat-links';
            $string = esc_attr__( 'Filed under: ', 'jkl' );
            
        } 
        
        // If the taxonomy type is 'tag'
        else if( 'tag' === $taxonomy_type ) {
            
            /* translators: used between list items, there is a space after the comma */
            $list = get_the_tag_list( '', esc_html__( ', ', 'jkl' ) );
            $search = ',';
            $separator = '';
            $test = $list;
            $class = 'tags-links';
            $string = esc_attr__( 'Tagged: ', 'jkl' );
            
        }
                
                if ( $test ) {
                        echo '<ul class="' . $class . '">';
                        echo $string;
                        
                        // So long as the Category list contains more items than our specified length, 
                        // we'll display the number of items specified, followed by a dropdown menu
                        // that houses the rest of the Categories
                        // Also note: -1 means we show ALL the categories without a dropdown
                        if( substr_count( $list, $search ) > $length && $length !== -1 ) {
                            
                            // For the number of specified items
                            for( $i = 1; $i <= $length; $i++ ) {
                                
                                // The Category will be the substring from the beginning of the string to the end of the first link </a> tag
                                $item = substr( $list, 0, ( strpos( $list, $search ) + strlen( $search ) ) );
                                
                                // If the NEXT item is the last item, give it a special CSS class to specify that
                                // just in case we want to style that one individually
                                if( $i == $length ) {
                                    echo str_replace( '<a ', '<a class="final-tax-link" ', $item );
                                } else {
                                    // otherwise, separate every Category with a comma
                                    echo $item . $separator;
                                }
                                // Now, remove that first category from the list (string) and continue the loop
                                $list = substr( $list, ( strpos( $list, $search ) + strlen( $search ) ) );
                            }
                            
                            // After looping through our specified number of Categories, output the rest of them in a dropdown menu
                            if( ! empty( $list ) ) {
                                echo '<span class="jkl-tax-switch"><i class="fa fa-angle-down"></i></span>';
                                printf( '<ul class="submenu dropdown">' . $list . '</ul>', $list ); // WPCS: XSS OK.     
                            }
                            
                        }
                            
                        // Else, in the case that our Category list is shorter than the specified $length
                        // OR  if we've specified -1 as the $length (to show all values)
                        else {
                            
                            // So long as we have Categories left in the string
                            while( $list !== '' ) {
                                
                                // Do the same as above, find the first Category and get ready to output it
                                $item = substr( $list, 0, ( strpos( $list, $search ) + strlen( $search ) ) );
                                
                                // If the Category list has only ONE Category (we check for a single </a> tag)
                                if( substr_count( $list, $search ) == 1 ) {
                                    // Output it without a comma
                                    echo $item;
                                } else {
                                    // Otherwise, separate the Categories with commas
                                    echo $item . $separator;
                                }
                                // Now, remove that first category from the list (string) and continue the loop
                                $list = substr( $list, ( strpos( $list, $search ) + strlen( $search ) ) );
                            }
                        }
                        
                        // Close the links list
                        echo '</ul>';
                        
		}
                
        } // END taxonomy list
        
}