title: nodejs request.url.match(regexp) seems to return a substring of the match in addition to the match
body: <p>I tried a piece of code like this</p>
  
  <pre><code>var match = req.url.match(/^\/user\/(.+)/)
  </code></pre>
  
  <p>And passed a url like so <code>"___http://someurl/user/jane"</code></p>
  
  <p>as it turned out match was initialized to an array with the following elements</p>
  
  <pre><code>match[0]='/user/jane'
  match[1]='jane'
  </code></pre>
  
  <p>I would have expected a single element i.e. the first element in <code>match[0]</code>. why was the second string returned -it doesn't seem to match the regex. </p>
  
  <p>My experience with JavaScript is minimal and I couldn't find an explanation after some looking around. Appreciate an explanation of this</p>
  
  <p>thanks</p>