ApiService.ts

type Result<Response> = {
  get(): Promise<Response>;
  delete(): Promise<Response>;
  post(body?: BodyInit): Promise<Response>;
  put(body?: BodyInit): Promise<Response>;
  patch(body?: BodyInit): Promise<Response>;
};

type Options = {
  headers?: Record<string, string>;
  params?: Record<string, string>;
};

export async function checkForV2Error(response: Response): Promise<Response> {
  if (!response.ok) {
    throw new Error(
      (await response.json())?.error?.message ?? 'Request failed',
    );
  }
  return response;
}

export function v2<Response = any>(
  endpoint: string,
  options: Options = {},
): Result<Response> {
  const { headers, params } = options;

  let input = `/v2/${endpoint}`;

  if (params) {
    input += `?${new URLSearchParams(params).toString()}`;
  }

  const init: RequestInit = {
    headers,
  };

  return {
    get(): Promise<Response> {
      return fetch(input, init)
        .then(checkForV2Error)
        .then((response) => response.json());
    },
    delete(): Promise<Response> {
      return fetch(input, {
        ...init,
        method: 'DELETE',
      })
        .then(checkForV2Error)
        .then((response) => response.json());
    },
    post(body?: BodyInit): Promise<Response> {
      return fetch(input, {
        ...init,
        headers: {
          ContentType: 'application/json',
          'X-CSRF-Token': typeof window !== 'undefined' && window.__CSRF_TOKEN,
          ...(init.headers || {}),
        },
        method: 'POST',
        body,
      })
        .then(checkForV2Error)
        .then((response) => response.json());
    },
    put(body?: BodyInit): Promise<Response> {
      return fetch(input, {
        ...init,
        headers: {
          ContentType: 'application/json',
          ...(init.headers || {}),
        },
        method: 'PUT',
        body,
      })
        .then(checkForV2Error)
        .then((response) => response.json());
    },
    patch(body?: BodyInit): Promise<Response> {
      return fetch(input, {
        ...init,
        headers: {
          ContentType: 'application/json',
          ...(init.headers || {}),
        },
        method: 'PATCH',
        body,
      })
        .then(checkForV2Error)
        .then((response) => response.json());
    },
  };
}

Usage:

v2('/markets').get()
  .then((data) => {
    // Do something with data
  }) ;