title: AS3 RegEx returns null
body: <p>Can anyone explain why the code below traces null when on the timeline?</p>
  
  <pre><code>var cleanRegExp:RegExp = /^[a-zA-Z0-9]+(\b|\/)/;
  var str:String = "/num83r5/and/letters/4/A/";
  trace(str.match(cleanRegExp.toString()));
  </code></pre>
  
  <p>I've read the documentation, so I'm pretty sure that I'm declaring the RegEx correctly and that <code>String.match()</code> should only return null when no pattern is passed in, otherwise it should be an array with 0+ elements.  I suspected a badly written expression, but surely that should still return an empty array?</p>
  
  <p><strong>EDIT:</strong> Both these trace "no matches" instead of either 5 or 0, depending on the expression being correct:</p>
  
  <pre><code>var cleanRegExp:RegExp = /^[a-zA-Z0-9]+(\b|\/)/;
  var str:String = "/num83r5/and/letters/4/A/";
  var res:Array = str.match(cleanRegExp);
  trace((res == null) ? "no matches" : res.length);
  </code></pre>
  
  <p>And:</p>
  
  <pre><code>var cleanRegExp:RegExp = /^[a-zA-Z0-9]+(\b|\/)/;
  var str:String = "/num83r5/and/letters/4/A/";
  var res:Object = cleanRegExp.exec(str);
  trace((res == null) ? "no matches" : res[0]);
  </code></pre>