title: What is the difference between collection.find with a callback and without?
body: <p>What is the difference between:</p>
  
  <pre><code>var cursor = collection.find();
  //do something
  </code></pre>
  
  <p>and</p>
  
  <pre><code>collection.find(null, function(err, cursor) {
    //do something
  }
  </code></pre>
  
  <p>Does the first one "block?" If so, does "block" mean that it will lock up node until mongo returns the cursor?</p>
  
  <p>(The first example is from the documentation for <a href="https://github.com/mongodb/node-mongodb-native#find" rel="nofollow">node-mongodb-native</a>. If their example is blocking, then why would they put in the documentation?)</p>