title: Check if a string is a date value
body: <p>What is an easy way to check if a value is a valid date, any known date format allowed. </p>
  
  <p>For example I have the values <code>10-11-2009</code>, <code>10/11/2009</code>, <code>2009-11-10T07:00:00+0000</code> which should all be recognized as date values, and the values <code>200</code>, <code>10</code>, <code>350</code>, which should not be recognized as a date value. What is the simplest way to check this, if this is even possible? Because timestamps would also be allowed.</p>