title: Loop over typescript Array asynchronously
body: <p>I have a typescript array <code>this.products</code>
  I need to loop over the elements of the array and for each element send parameters to Angular service which makes an API call and gets an answer to the client as an Observable. However, due to asynchronous nature of Observable, my loop finishes before all of the answer are sent back from the server.
  This is my code:</p>
  
  <pre><code>this.products.forEeach((ele, idx) =&gt; {
       this.myService.getSomeDetails(ele.prop1, ele.prop2).subscribe(result =&gt; {
           // do something with result 
       });   
  });
  </code></pre>
  
  <p>I need for the loop to advance only after the completion of each observable subscription. How can I implement it? Thanks.</p>