title: Insert field with $currentDate to MongoDB collection in Meteor
body: <p>Not sure how to use <a href="http://docs.mongodb.org/manual/reference/operator/update/currentDate/" rel="noreferrer">$currentDate</a> when inserting a document into a MongoDB collection in Meteor. </p>
  
  <p>Can this only be used in an update, not an insert? Would seem strange, but I don't see an alternative (other than using <code>new Date</code> instead).</p>
  
  <p><strong>Example</strong></p>
  
  <pre><code>Stuff.insert({ 
     owner: Meteor.userId(),
     createdAt: ..., // how to create this field with $currentDate ?
     theStuff: "Some of the good stuff"
  })
  </code></pre>
  
  <p><strong>Notes / Thoughts / TL,DR</strong> </p>
  
  <ul>
  <li>Fields can't start with $ operators or, as far as I know, curly braces <code>{}</code>.</li>
  <li>What's the point of having an operator that only works with updates, if that's indeed the case?</li>
  <li>Why/when is <code>$currentDate</code> better than <code>new Date</code>? </li>
  <li>One nice thing, if using Moment.js esp, is that $currentDate is entered in ISO 8601 format.</li>
  <li>Is the answer to do some kind of upsert from the start? If so, could this have unintended consequences?</li>
  </ul>