title: IE and Firefox regular expression question
body: <p>Why the following pattern in IE and Firefox matches result different?</p>
  
  <pre><code>var str = 'a,b,c , d,   e   ,f';
  var matches = str.split(/(\s+)?,(\s+)?/);
  alert(matches);
  
  IE: 
  a,b,c,d,e,f
  
  firefox: 
  a,,,b,,,c, , ,d,,   ,e,   ,,f
  </code></pre>
  
  <p>how to match like IE result?
  please answer me :(</p>
  
  <p>ie8 and firefox v3.6.8</p>