title: regex exclude certain tags
body: <p>just need a quick help for solving this problem.</p>
  
  <p>I want to strip all html tags out of a string except the tags from a whitelist(variable).</p>
  
  <p>My code so far:</p>
  
  <pre><code>whitelist = 'p|br|ul|li|strike|em|strong|a', 
  reqExp = new RegExp('&lt;\/?[^&gt;|' + whitelist + ']+\/?&gt;');
  </code></pre>
  
  <p>The problem is now it works more or less fine but also not removing for example <code>b</code> because it matches the <code>b</code> from the <code>br</code> out of the whitelist.</p>
  
  <p>I tried different approaches but dont find the right solution.
  How can i tell the regex to do something like <code>/.WITHOUT(smth)/</code> (therefore: match all expect everything following).</p>