我想你的问题是ajaxurl 对于您的脚本不可用。在加载js代码之前，尝试定义该变量。最好的方法是使用wp\\u localize\\u脚本：

PHP：

add_action( \'wp_enqueue_scripts\', \'cyb_enqueue_scripts\' );
function cyb_enqueue_scripts() {
    //Change the key and url with yours
    wp_register_script(\'my-js\', get_stylesheet_directory_uri(). \'/js/my-js.js\', array( \'jquery\' ) );
    wp_enqueue_script(\'my-js\');

    //Localize script data to be used in my-js.js
    $scriptData = array();
    $scriptData[\'ajaxurl\'] = admin_url( \'admin-ajax.php\' );
    $scriptData[\'action\'] = \'voteIncrement\';

    wp_localize_script( \'my-js\', \'my_js_data\', $scriptData );

}


add_action("wp_ajax_voteIncrement", "voteIncrement");
add_action("wp_ajax_nopriv_voteIncrement", "voteIncrement");

function voteIncrement(){

    echo \'hello\';
    die();
}

(function($){
    $(document).ready(function(){
        $(\'.btn-vote\').on(\'click\',function(e){

            e.preventDefault();
            var $that = jQuery(this);
            var id = $that.attr(\'data-id\');
            var data = {
                \'action\': my_js_data.action,
                \'id\': id
            };

            jQuery.post( my_js_data.ajaxurl, data, function(response) {
                console.log(response);
                $that.find(\'.vote-count\').html(response);
            });

        });
    });
})(jQuery);