fetchJson

fetchJson.js

// Based on: https://jsfiddle.net/t2g9ub43/1/
const fetchJson = async (url, { ...opts } = {}) => {
  opts.headers = new Headers(opts.headers);
  opts.headers.set('Accept', 'application/json');
  return fetch(url, opts).then((resp) => {
    const ct = resp.headers.get('content-type');
    if (!ct || !ct.includes('application/json')) {
	    throw resp;
    }
    return resp.json().then((json) =>
      Object.assign(resp, { json }),
    );
  });
};

fetchJson('https://jsonplaceholder.typicode.com/todos/1').then(
  console.log,
  console.error,
);