Since this is the first time front-end development experience, I need put google calendar on my webApp, but google oauth didn’t give me the refresh_token to do CRUD on calendar

I knew the google oauth process is:

1. sent request url to google oauth server
2. google prompts user for consent
3. get oauth server response :
   the response is like

{
  'access_token':...,
  'expires_in':...,
  'scope':...,
  ...,
  'refresh_token:,
}

i’ve ask chatgpt that need set access_type='offline' and prompt: 'consent', but it can’t work

the partial code is blew:

 function gisLoaded() {
    tokenClient = google.accounts.oauth2.initTokenClient({
      client_id: CLIENT_ID,
      scope: SCOPES,
      callback: '', // defined later
      access_type: 'offline',
      prompt: 'consent'
    });
    gisInited = true;
    maybeEnableButtons();
  }

  function maybeEnableButtons() {
    if (gapiInited && gisInited) {
      // Enable the authorize button here
    }
  }

  function handleAuthClick() {
    tokenClient.callback = async (resp) => {
      if (resp.error !== undefined) {
        throw (resp);
      }
      setIsAuthorized(true);
      setAuthToken(gapi.client.getToken().access_token);  // Save the token
      await createNewCalendar();
    };

    if (gapi.client.getToken() === null) {
      tokenClient.requestAccessToken({ prompt: 'consent' });
    } else {
      tokenClient.requestAccessToken({ prompt: '' });
    }
  }

the response from google, which lack of refresh_token field

Can anyone help me?
greatly appreciated! thanks