title: How to set an initial value for an object key?
body: <p>I have an object, where the user is an object, and firstly I check from an array if one of it's elements equals to the criteria. It's not always the case, and if it doesn't exist in the array, I want to return an empty object (instead of <code>undefined</code>):</p>
  
  <pre class="lang-js prettyprint-override"><code>//...
  return {
    user: users.find(user =&gt; user.uid === selectedUser)
  }
  </code></pre>