title: Positive Lookbehind not supported on javascript
body: <p>I'm trying to match the following string <code>a2eaa37edefd4a1e9bb0d082e441cd4e</code></p>
  
  <p>When trying my regex in node, I'm getting <code>Invalid regular expression, valid group</code> </p>
  
  <p>I have learned that not all flavors of javascript supports positive lookbehind</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>var url = 'http://file-store.example.local/files/a2eaa37edefd4a1e9bb0d082e441cd4e+1a3e5372-8fb2-44df-82ed-5603e3a1d72c'
  
  var regex = /(?&lt;=files\/)(.*?)(?=\+|\-)/g;
   
  console.log(url.match(regex));</code></pre>
  </div>
  </div>
  </p>
  
  <p>Any ideas on how I can get same results with different regex? </p>