title: What's difference between Q.nfcall and Q.fcall?
body: <p>I am new to node.js. I am trying to understand Q.nfcall.
  I have the following Node.js code. </p>
  
  <pre><code>function mytest() {
    console.log('In mytest');
    return 'aaa';
  }
  
  Q.nfcall(mytest)
  .then(
    function(value){
      console.log(value);
  });
  </code></pre>
  
  <p>My expected output should be:</p>
  
  <pre><code>In mytest 
  aaa
  </code></pre>
  
  <p>But the actual output is:</p>
  
  <pre><code>In mytest
  </code></pre>
  
  <p>After I changed Q.nfcall to Q.fcall in the code above, the output became what I expected:</p>
  
  <pre><code>In mytest 
  aaa
  </code></pre>
  
  <p>Why's that? What's difference between Q.nfcall and Q.fcall? Thanks.</p>