title: Prevent moment.js accepting an integer as a valid ISO8601 date
body: <p>I have some API's for creating dashboard widgets.  Those API's return basic name/value data pairs that are passed to Google Charts.  Moment.js checks whether the value is an ISO8601 date, and if so passes to Google Charts as a date instance.</p>
  <p>However, the <code>ISO_8601 isValid</code> check is currently returning true if the date is a simple integer, e.g. <code>1234</code>:</p>
  <pre><code>var myInt = 1234;
  if (moment(myInt, moment.ISO_8601, true).isValid()) {
      console.log(&quot;Valid!&quot;);
  }
  </code></pre>
  <p>I couldn't locate the necessary functionality to force a date format in the moment.js code, so this brutal hack works for now:</p>
  <pre><code>var myInt = 1234;
  if (JSON.stringify(myInt).includes(&quot;T&quot;) &amp;&amp; moment(myInt, moment.ISO_8601, true).isValid()) {
      console.log(&quot;Valid!&quot;);
  }
  </code></pre>
  <p>Is there a <strong>correct</strong> way to use moment.js to configure the <code>isValid()</code> check?</p>
  <p>The date format from my API is <code>yyyy-mm-ddThh:mm:ss</code> (without <code>Z</code> on the end).</p>