title: Angular RX get zip file and unzip it
body: <p>
  I am getting a zip file from backend and I need to unzip it's contents (bunch of json files for big offline data). </p>
  
  <p>Api call: </p>
  
  <pre class="lang-js prettyprint-override"><code>getOfflineTimetables() {
      let req = new Request(myOptions);
      return this.http.request(req)
          .map(res =&gt; {
              return res;
          })
  }
  </code></pre>
  
  <p>When I was getting regular jsons, I just mapped it res.json()</p>
  
  <p>For the zip I don't know how to map it, without mapping it doesn't work.</p>
  
  <p>In my other service I am subscribing to getOfflineTimetables, but I don't how to pass the zip to my unzip(file) method. I am trying to write the file to file system and then unzip it.</p>
  
  <pre class="lang-js prettyprint-override"><code>this.api.getOfflineTimetables().subscribe(res =&gt; {
      this.writeFile(res).then(written =&gt; {
          this.unzip(written);
      }
  }
  </code></pre>
  
  <p>My problem is I can't get to the zip file from the Api call.</p>