feed-parser.js

const FeedParser = {
  fetchXML(url) {
    return new Promise((resolve, reject) => {
      let request = new XMLHttpRequest();
      request.open("GET", url, true);

      request.addEventListener("load", (event) => {
        if (request.responseXML) {
          resolve(request.responseXML);
        } else {
          reject(new Error(request.statusText));
        }
      });

      request.send();
    });
  },
  async getFeed(url) {
    const doc = await this.fetchXML(url);
    const feed = this.parseFeed(doc);
    feed.feedUrl = url;
    return feed;
  },
}