title: Javascript - check if key exists - if not create it, all in one line
body: <p>I'm looking for a one-liner way of checking if a key exists and if it doesn't create it.</p>
  
  <pre><code>var myObject = {};
  
  //Anyway to do the following in a simpler fashion?
  
  if (!('myKey' in myObject))
  {
      myObject['myKey'] = {};
  }
  </code></pre>