title: Luxon.js get difference between now and input date in years
body: <p>I'm using luxon.js and want to check, is the user's age is over than 21 years.
  Code, that i'm using for it</p>
  
  <pre><code>const isTooYoung = date =&gt;
    DateTime.fromFormat(date, 'dd.MM.yyyy')
      .diffNow()
      .as('years') &lt; -21;
  </code></pre>
  
  <p>But for todays' s day (18.11.2019) both calls:</p>
  
  <pre><code>console.log(isTooYoung('15.11.1998')); // true =&gt; incorrect
  console.log(isTooYoung('20.11.1998')); // true =&gt; correct, this user is not 21 year old yet
  </code></pre>
  
  <p>fiddle: <a href="http://jsfiddle.net/zh4ub62j/1/" rel="noreferrer">http://jsfiddle.net/zh4ub62j/1/</a></p>
  
  <p>So, what is correct way to solve problem to check, is the user's age is over than x years?</p>