title: Convert Dates with Regular Expression 1/1/18 -> 2018-01-01
body: <p>I have dates that are in <strong>m/d/yy</strong> but need to convert them to <strong>yyyy-dd-mm</strong> format. I have the following regex
  <code>(\d{1,2})\/(\d{1,2})\/(\d{1,2})</code> with this replace <code>20$3-$1-$2</code>. I'm assuming year 2000 which is okay but this breaks for single digit days and months. </p>
  
  <p>Is there any way to prefix the days and months with 0 if the match is on a single digit?</p>