custom fetcher

fetch.js

class ResponseError {
  constructor(response) {
    this.response = response;
  }

  async read() => {
    return this.response
      .text()
      .then(body => {
        return {
          url: this.response.url,
          code: this.response.status
          text: this.response.statusText
          body: body
        };
      });
  }
}


class Request() {
  constructor(request) {
    this.request = request;
  }

  async send() {
    fetch(this.request)
      .then(response => {
        if (response.ok) {
          return response;
        }
        throw new ResponseError(response);
      })
      .then(response_ok => {
        return response_ok.json();
      })
      .then(body => {
        // FIXME: We assume the body contains valid JSON here
        return JSON.stringify(body, null, 4);
      })
      .catch(e => {
        if (e instanceof ResponseError) {
          // FIXME: Is await ok here?
          throw new RequestFailed(await response.read());
        } else {
          throw new RequestFailed(e.toString());
        }
      });
  }
}