Simple ponyfill for QuickJS

fetch.js

import * as os from 'os';
import * as std from 'std';

function mapToFetchResponse(fullResponse) {
  const {
    responseHeaders,
    status,
    response,
  } = fullResponse;

  const headerEntries = responseHeaders.trim().split('\n').map(line => {
    const [key, value] = line.split(':');
    return [key.trim(), value.trim()];
  });

  return {
    status,
    headers: Object.fromEntries(headerEntries),
    ok: status >= 200 && status <= 299,
    async json() {
      return JSON.parse(response)
    },
    async text() {
      return response;
    }
  }
}

export default async function fetch(url, options) {
  if (options) {
    throw new Error('Fetch options not supported');
  }

  return new Promise((resolve, reject) => {
    const worker = new os.Worker(`
      import * as os from 'os';
      import * as std from 'std';
      const parent = os.Worker.parent;
      parent.onmessage = (event) => {
        const [url, options] = event.data;
        const data = std.urlGet(url, { full: true });
        parent.postMessage(data);
      }
    `);

    worker.onmessage = (event) => {
      if (event.data.status) {
        resolve(mapToFetchResponse(event.data));
      } else {
        reject('Request failed');
      }

      worker.onmessage = null;
    }
    worker.postMessage([url, options]);
  })
}