title: Multiple optional route parameters in Express?
body: <p>I am using Express to handle a route which is in the format of <code>/articles/:year/:month/:day</code>, where year, month and day are optional.</p>
  
  <ul>
  <li>If none of the three params is given, all articles will be returned;</li>
  <li>If year is given, articles of that year will be returned;</li>
  <li>If year and month are given, articles of that year and month will be returned;</li>
  <li>If all three params are given, articles of that year, month and day will be returned.</li>
  </ul>
  
  <p>My question is, how do I make them optional? With the current route I've defined, unless all three parameters are present, it will not be able to be resolved and will fall into the default route.</p>