title: regex date without the zero
body: <p>I need to be able to allow dates in the format MM/DD/YYYY where the leading month and day can have a leading zero or not where appropriate </p>
  
  <p>In other words: 
  01-09 or 1-9 are acceptable months</p>
  
  <p>01-09 or 1-9 are acceptable days</p>
  
  <p>I am very close with this:</p>
  
  <pre><code>/(0[1-9]|1[0-2])\/(0[1-9]|1[0-9]|2[0-9]|3(0|1))\/\d{4}/
  </code></pre>
  
  <p>With my limited knowledge I thought doing this would allow for a leading zero (or not)</p>
  
  <pre><code>/(0?[1-9]|1[0-2])\/(0[1-9]|1[0-9]|2[0-9]|3(0|1))\/\d{4}/
  </code></pre>
  
  <p>But that allows for dates such as 13/31/2008, for reasons I can't explain.</p>
  
  <p>Question:
  I need a regular expression that allows all possible dates in the format MM/DD/YYYY where the month or day can contain leading zeros (or not) where both will pass.</p>
  
  <p>Edit:</p>
  
  <p>I am working with a 3rd party system that fails downstream if a user’s input is not a real date. The only tool I have against the input is Regex check. (For those that down voted my question)</p>