spee.ch/react/utils/request.js

/**
 * Parses the JSON returned by a network request
 *
 * @param  {object} response A response from a network request
 *
 * @return {object}          The parsed JSON from the request
 */
function parseJSON (response) {
  if (response.status === 204 || response.status === 205) {
    return null;
  }
  return response.json();
}

/**
 * Parses the status returned by a network request
 *
 * @param  {object} response   A response from a network request
 * @param  {object} response   The parsed JSON from the network request
 *
 * @return {object | undefined} Returns object with status and statusText, or undefined
 */
function checkStatus (response, jsonResponse) {
  if (response.status >= 200 && response.status < 300) {
    return jsonResponse;
  }
  const error = new Error(jsonResponse.message);
  error.response = response;
  throw error;
}

/**
 * Requests a URL, returning a promise
 *
 * @param  {string} url       The URL we want to request
 * @param  {object} [options] The options we want to pass to "fetch"
 *
 * @return {object}           The response data
 */

export default function request (url, options) {
  return fetch(url, options)
    .then(response => {
      return Promise.all([response, parseJSON(response)]);
    })
    .then(([response, jsonResponse]) => {
      return checkStatus(response, jsonResponse);
    });
}