title: How to convert date(different formats) to epoch format at a time
body: <p>I have the dates of different formats I just want to convert them all to epoch format at a time.</p>
  
  <p>The date formats are like any of below formats :</p>
  
  <pre><code>1. "October 1, 2018"
  2. "23/05/2018"
  3. "20-02-2017"
  4. "May 2016"
  </code></pre>