title: optional characters in javascript regular expression
body: <p>I am trying to build a regular expression in javascript that checks for 3 word characters however 2 of them are are optional.  So I have:</p>
  
  <p>
  <code>
   /^\w\w\w/i
  
  
  </code>
  </p>
  
  <p>what I am stumped on is how to make it that the user does not have to enter the last two letters but if they do they have to be letters</p>