You can define the json format by yourself according to your needs. There is nothing more to say about the next two questions

• The http status value is 422, which seems to be hard-coded in the framework. I want to return custom json to the front end by catching validation exceptions. Is this possible?

  <?php
  namespace App\Exceptions;
  
  use Illuminate\Validation\ValidationException;
  ...
     
  class Handler extends ExceptionHandler
  {
      ...
      
      public function render($request, Exception $e)
      {
          if ($request->ajax() || $request->wantsJson()) {
              $errors = [];
              if ($e instanceof ValidationException && $e->getResponse()) {
                  try {
                      $errors = json_decode($e->getResponse()->getContent(), true);
                  } catch (\Exception $ex) {
                      $errors = $e->getResponse()->getContent();
                  }
              }
  
              return response()->json([
                  'message'     => empty($errors) ?
                      (empty($e->getMessage()) ? '出错了' : $e->getMessage())
                      : implode(',', array_first($errors)),
                  'status_code' => $e->getStatusCode(),
                  'errors'      => $errors
              ]);
          }
          ...
      }
  }

• Using jquery's ajax method, when an error occurs, you still cannot get the return data formatted as a json object, you can only get a json in the form of a string

  $.ajax({
      ...
      dataType: "json",
      ...