这里有一个功能齐全的代码片段。

我添加了正确的WordPress表格样式这需要添加我的smyles_get_taxonomy_hierarchy 要将分类法的子对象添加到术语对象，如果不存在子对象，则会隐藏子下拉列表，这将根据TERM ID 不是NAME .. 您应该始终使用术语ID，就好像您决定以后更改措辞/slug一样，您将遇到各种问题

这里的代码语法highlighter似乎无法处理HTML/JS/PHP的混合，所以这里有一个GitHub工作代码要点：https://gist.github.com/tripflex/527dd82db1d1f3bf82f761486fcc3303

细分：

首先需要包含my函数，以生成该术语对象中包含子对象的分类法数组：

if ( ! function_exists( \'smyles_get_taxonomy_hierarchy\' ) ) {
    /**
     * Recursively get taxonomy and its children
     *
     * @param string $taxonomy
     * @param int    $parent Parent term ID (0 for top level)
     * @param array  $args   Array of arguments to pass to get_terms (to override default)
     *
     * @return array
     */
    function smyles_get_taxonomy_hierarchy( $taxonomy, $parent = 0, $args = array( \'hide_empty\' => false ) ) {

        $defaults = array(
            \'parent\'     => $parent,
            \'hide_empty\' => false
        );
        $r        = wp_parse_args( $args, $defaults );
        // get all direct decendants of the $parent
        $terms = get_terms( $taxonomy, $r );
        // prepare a new array.  these are the children of $parent
        // we\'ll ultimately copy all the $terms into this new array, but only after they
        // find their own children
        $children = array();
        // go through all the direct decendants of $parent, and gather their children
        foreach ( $terms as $term ) {
            // recurse to get the direct decendants of "this" term
            $term->children = smyles_get_taxonomy_hierarchy( $taxonomy, $term->term_id );
            // add the term to our new array
            $children[ $term->term_id ] = $term;
        }

        // send the results back to the caller
        return $children;
    }
}

jQuery/JavaScript代码处理：

jQuery( function($){
    // slcustom_categories var should be available here
    $(\'#parent_category\').change( function(e){
        var child_cat_select = $( \'#child_category\' );
        var term_id = $(this).val();

        console.log( \'Parent Category Changed\', term_id );

        // Remove any existing
        child_cat_select.find( \'option\' ).remove();

        // Loop through children and add to children dropdown
        if( slcustom_categories && slcustom_categories[ term_id ] && slcustom_categories[ term_id ][\'children\'] ){
            console.log( \'Adding Children\', slcustom_categories[ term_id ][\'children\'] );
            $.each( slcustom_categories[term_id][\'children\'], function( i, v ){
                console.log( \'Adding Child: \', v );
                child_cat_select.append( \'<option value="\' + v[\'term_id\'] + \'">\' + v[ \'name\' ] + \'</option>\');
            });

            // Show if child cats
            $( \'#child_category_row\' ).show();
        } else {
            // Hide if no child cats
            $( \'#child_category_row\' ).hide();
        }
    });

    // Trigger change on initial page load to load child categories
    $(\'#parent_category\').change();
});

输出字段的函数：

function slcustom_user_profile_fields( $user ){

    $categories = smyles_get_taxonomy_hierarchy( \'project_category\' );
    $parent_category = $user->parent_category;
    $child_category = $user->child_category;
//  $parent_category = 52; // used for testing
//  $child_category = 82; // used for testing
    $parent_has_children = ! empty( $parent_category ) && $categories[ $parent_category ] && ! empty( $categories[ $parent_category ]->children );

    // Creative way to use wp_localize_script which creates a JS variable from array
    // You should actually change this to load your JavaScript file and move JS below to that file
    wp_register_script( \'slcustom_user_profile_fields\', \'\' );
    wp_localize_script( \'slcustom_user_profile_fields\', \'slcustom_categories\', $categories );
    wp_enqueue_script( \'slcustom_user_profile_fields\' );
    ?>
    <h1 id="temppp">Select a parent taxonomy</h1>
    <table class="form-table">
        <tbody>
            <tr>
                <th>
                    Parent
                </th>
                <td>
                    <select name="parent_category" id="parent_category">
                    <?php
                        foreach( (array) $categories as $term_id => $cat ){
                            ?>
                            <option value="<?php echo esc_attr( $term_id ) ?>"<?php echo selected( $parent_category, $term_id ); ?>><?php echo $cat->name; ?></option>
                            <?php
                        }
                    ?>
                    </select>
                </td>
            </tr>
            <tr id="child_category_row" style="<?php if( ! $parent_has_children ){ echo \'display: none;\'; }?>">
                <th>
                    Child
                </th>
                <td>
                    <select name="child_category" id="child_category">
                        <?php
                            if( $parent_has_children ){
                                foreach( (array) $categories[$parent_category]->children as $c_term_id => $child ){
                                    ?>
                                    <option value="<?php echo esc_attr( $c_term_id ) ?>"<?php echo selected( $child_category, $c_term_id ); ?>><?php echo $child->name; ?></option>
                                    <?php
                                }
                            }
                        ?>
                    </select>
                </td>
            </tr>
        </tbody>
    </table>
    <?php
}