title: Intl.DateTimeFormat returns an hour over 24
body: <p>I have the following Unix timestamp: <code>1611328500000</code> (<code>Fri Jan 22 2021 10:15:00 GMT-0500 (Eastern Standard Time)</code>).</p>
  <p>I need to display it in Korean Standard Time. To do so, I'm using <code>Intl.DateTimeFormat</code>. However, for some reason, the result I'm getting is <strong>24:15</strong> when I attempt to format it. Unless I'm delusional, I'm pretty sure that's higher than a 24-hour clock usually goes (0:00 to 23:59).</p>
  <p>Google tells me my result should be <strong>0:15</strong>, obviously on the following date (Sat Jan 22).</p>
  <p>Here's a minimal working example:</p>
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>const date = new Date(1611328500000);
  
  const timeOptions = {
    hour12: false,
    hour: '2-digit',
    minute: '2-digit'
  };
  
  const formatter = new Intl.DateTimeFormat('en-US', {
    timeZone: 'Asia/Seoul', ...timeOptions
  });
  
  console.log(formatter.format(date));</code></pre>
  </div>
  </div>
  </p>
  <p>Am I crazy? Can times go up to 24:15 in some circumstances? What is happening here?</p>
  <hr />
  <p><strong>EDIT</strong>: I just found <a href="https://github.com/formatjs/formatjs/issues/1577" rel="nofollow noreferrer">this page</a> which seems to be experiencing a similar problem. The answer provided there points me towards something called <code>hourCycle</code>, with a link to MDN's <code>Intl.DateTimeFormat</code>.</p>
  <p>However, <code>hourCycle</code> only appears once on that page, in the browser support section. Adding the suggested <code>hourCycle: h11</code> to my <code>timeOptions</code> did not work.</p>
  <p>Digging further, I found <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/Locale/hourCycle" rel="nofollow noreferrer">this page</a>, which lists <code>h23</code> as a valid option. Surely this is what I'm after! But, alas... my result is still 24:15.</p>