请尝试下面的代码片段。

HTML :

<input name="getUser" id="getUser" value=\'\'/>
<div id="user_data"></div>

JS (js/my-ajax-script.js)

 jQuery(document).ready(function($){
    $(\'#getUser\').keyup(function(e) {
      var user_id = e.target.value;
      console.log(user_id);
      $.ajax({
            url:my_ajax_object.ajaxurl, #add here your ajax url
            type:\'POST\',
             data:\'action=get_this_user_data&user_id=\'+user_id ,
             success:function(results)
             {
              jQuery(\'#user_data\').html(results);

             }
        });
    });
});

Ajax (add in functions.php)

function my_enqueue() {

wp_enqueue_script( \'ajax-script\', get_template_directory_uri() . \'/js/my-ajax-script.js\', array(\'jquery\') );

wp_localize_script( \'ajax-script\', \'my_ajax_object\',
        array( \'ajax_url\' => admin_url( \'admin-ajax.php\' ) ) );
   }
   add_action( \'wp_enqueue_scripts\', \'my_enqueue\' );

add_action( \'wp_ajax_get_this_user_data\', \'get_this_user_data\' );
add_filter( \'wp_ajax_nopriv_get_this_user_data\', \'get_this_user_data\');
function get_this_user_data()
{
    $userid = $_POST["user_id"];
    $data = \'\';
    $user_info = get_userdata($userid);
     if(!empty($user_info))
     {
       $data .= \'<pre>\';
       $data .= \'Username: \' . $user_info->user_login . \'<br/>\';
       $data .= \'User roles: \' . implode(\', \', $user_info->roles) . \'<br/>\';
       $data .= \'User ID: \' . $user_info->ID . \'<br/>\';
       $data .=\'</pre>\';
     }
     else
     {
        $data = "user data not found";
     }

      echo $data;
      die();
}