I want to use class Api component for my react app. It is look like this with method getCards:
getCheck(res: any) {
  return res.ok ? res.json() : new Promise.reject("fail");
}
getCards() {
  const requestOptions:any = {
    method: "GET",
    headers: this.header,
    redirect: "manual"
  };
  return fetch("/oapi/privelege/getAllPrivilege", requestOptions)
    .then((res) => {
      return this.getCheck(res);
    });
}
In my App component I call this method: const res = api.getCards();
But in my console I do not see data. It's just promise. Why? How I can use res with data in my App component?
 
    