title: How to union 3 regular expression?
body: <pre><code>M/D/YY    /^(\d{1,2})\/(\d{1,2})\/(\d{2})$/           
  M-D-YY    /^(\d{1,2})\-(\d{1,2})\-(\d{2})$/
  M.D.YY    /^(\d{1,2})\.(\d{1,2})\.(\d{2})$/
  </code></pre>