title: Is each tab in a browser single or multi-threaded?
body: <p>I know that a each tab has its own process but is each tab also running in a single thread?</p>
  
  <p>My assumption would be that the javascript has it's own thread and another thread for doing things such as http calls.</p>
  
  <p>I'm doing a test to try and demo this by doing an http call with a lag time however I notice that when the http call actually happens I see no evidence of it in the devtools till I get a reply which would be consistent with single threaded unless it was designed that way.  Anyone have any insight into this?</p>
  
  <p>Javascript</p>
  
  <pre><code>this.http.get(this.staffUrl)
           .toPromise()
           .then(response =&gt; response.json() as Staff[])
           .catch(this.handleError);
  </code></pre>
  
  <p>PHP</p>
  
  <pre><code>public function index()
  {
      sleep(5);
      return response(DemoStaff::all(), 200);
  }
  </code></pre>
  
  <p>Thanks</p>