title: Typeahead Invalid regular expression: /(/:
body: <p>I've add a typeahead search. Everithing is working but I've found one issue. I have text in my json for example <strong><em>"Hi, my name is Jason (Mckay) and ..."</em></strong>
  <br/>
  <br/>
  When I try to type some words from this string everithin is ok, but when I'll type "<strong>(</strong>" or "<strong>)</strong>" I will have an exception: <br/></p>
  
  <pre><code>Uncaught SyntaxError: Invalid regular expression: /(/: Unterminated group
  </code></pre>
  
  <p>I was look into typeahead "the Basics" and have the same error: <br/> <br/><a href="https://twitter.github.io/typeahead.js/examples/#prefetch" rel="nofollow noreferrer">https://twitter.github.io/typeahead.js/examples/#prefetch</a>
  <br/><br/>
  The same when I'll try to input any nubmers first <strong>"1"</strong>, <strong>"2"</strong> etc...</p>
  
  <p>Here is my default substringMatcher where is the problem: <br/></p>
  
  <pre><code>var substringMatcher = function(strs) {
        return function findMatches(q, cb) {
          var matches, substringRegex;
  
          // an array that will be populated with substring matches
          matches = [];
  
          // regex used to determine if a string contains the substring `q`
          substrRegex = new RegExp(q, 'i');
  
          // iterate through the pool of strings and for any string that
          // contains the substring 'q', add it to the 'matches' array
          $.each(strs, function(i, str) {
            if (substrRegex.test(str)) {
              matches.push(str);
            }
          });
          cb(matches);
        };
      };
  </code></pre>