title: Require string input for moment to be of certain format
body: <p>It doesn't seem like moment's date parsing functionality is working as I would expect it.  The <a href="http://momentjs.com/docs/#/parsing/string-format/" rel="nofollow noreferrer">documentation</a> says the following:</p>
  <blockquote>
  <p>If you know the format of an input string, you can use that to parse a moment.</p>
  <p><code>moment(&quot;12-25-1995&quot;, &quot;MM-DD-YYYY&quot;);</code></p>
  </blockquote>
  <p>I have the following code:</p>
  <pre><code>moment(value, &quot;MM/DD/YYYY&quot;);
  </code></pre>
  <p>As I'm testing, I'm entering strings that do not adhere to the <code>MM/DD/YYYY</code> and yet they are parsed successfully as valid moment date.</p>
  <p>For example, <code>1-1-asdf</code> resolves to <code>01/01/2018</code>.</p>
  <p>How can I specify one or more date formats that should be used for string parsing and if it does not match a specified format, the parsed moment will be invalid?</p>