commerce/lib/shopify/ajax.ts

interface ErrorMessage {
  message: string;
}

export class AjaxError extends Error {
  statusCode: number;
  errors: ErrorMessage[];

  constructor(statusCode: number, message: string, errors: ErrorMessage[] = []) {
    super(message);
    this.errors = errors;
    this.statusCode = statusCode;
  }
}

type AjaxMethod = 'GET' | 'POST' | 'PUT' | 'PATCH' | 'DELETE';

export const ajax = async <T>(method: AjaxMethod, url: string, data?: object): Promise<T> => {
  const response = await fetch(url, {
    method,
    credentials: 'include',
    headers: {
      'Content-Type': 'application/json',
      Accept: 'application/json'
    },
    body: data ? JSON.stringify(data) : undefined
  });

  const body = await response.json();
  if (response.ok) {
    return body as T;
  }

  throw new AjaxError(response.status, body.message ?? response.statusText, body.errors);
};