title: What is the semantics and functionality of file scope return?
body: <p>It's all in the title.
  One part of my coding style is adding <code>return</code> whenever a function with a callback parameter is called, e.g.:</p>
  
  <pre><code>(function() {
      return whatever(function() /* callback */ { // Note the "return" keyword here
          // ...
      });
  })();
  </code></pre>
  
  <p>For quite a while, I have been using the same construct for file scope function calls with a callback parameter, but I wonder if this can cause side-effects I am not aware of.</p>
  
  <p>I could not find any documentation on the subject, and was unable to find out what it does.</p>
  
  <p>Thanks!</p>
  
  <p>[<strong>tl;dr</strong>] What does using the <code>return</code> keyword mean at file scope and what does it do?</p>