title: Queuing promises
body: <p>I use <a href="https://github.com/mbostock/queue" rel="noreferrer">mbostock/queue</a> for queuing few async operation. It is more to rate limit (UI generate few events, where the backend can process it slowly), and also to make sure they are processed   sequentially. I use it like</p>
  
  <pre><code>function request(d, cb) {
   //some async oper
   add.then(function(){
     cb(null, "finished ")
   })
  }
  
  var addQ = queue(1);
  addQ.defer(request) //called by few req at higher rates generated by UI
  </code></pre>
  
  <p>I already uses angular.js $q for async operation. So, do I have to use <code>mbostock/queue</code>, or can I build a queue out of <code>$q</code> (which is in spirit <a href="https://github.com/kriskowal/q" rel="noreferrer">https://github.com/kriskowal/q</a>)</p>
  
  <p>Thanks.</p>