title: Load and process files in parallel with Promise.all
body: <p>I want to load <em>and</em> <strong>process</strong> files in parallel. My Problem is that the data processing in my subscription  isn't run asynchrously, only the http fetch. How can I also make the data processing in parallel?</p>
  <pre><code>await Promise.all(requestsArray.map((request) =&gt; {
        return new Promise((resolve, reject) =&gt; {
          this.http.post(request, new FormData()).subscribe(async json =&gt; {
            console.log('load data in parallel from API for ' + request);
  
            mylongprocessingfunction(json); // blocks further processing of other files
  
            resolve(json);
  
          }, error =&gt; {
            console.log(error)
            reject({ error: error });
          });
  
        });
      }));
  </code></pre>