title: PHP regex ignores all symbols except letters
body: <p>I am trying to return true, if $str does not contains 'script+'.
  It blocks only 'script', but not 'script+'...</p>
  
  <p>How can i fix it?</p>
  
  <pre><code>if (!preg_match('/[\bscript+\b]/u', $str))
  return true;
  else
  return false;
  </code></pre>