title: Compute Keycloak client attribute using scriptMapper
body: <p>I'm using Keycloak as an Open ID connect provider, 
  I want to connect my keycloak instance to a service through OpenId.
  But this services requires user info to provide a numeric identifier (which keycloak does not provides).
  I thought I could use the script mapper for that task and takes key cloak internal id (an uuid) and generate a numeric id from it.</p>
  
  <p>The script mapper is supposed to accept javascript but there is no documentation nor playground to help me debug results.</p>
  
  <p>This piece of code seems to work but I can't manage to get the result in my user info.</p>
  
  <pre><code>var id = user.Id.replace(/-/g, '').substring(0,10);
  var fake_id = parseInt(id, 16);
  fake_id
  </code></pre>
  
  <p>This code is accepted but i cannot debug it.
  when I try <code>return fake_id;</code> I get the error :
  <code>Invalid return statement return fake_id;</code> </p>
  
  <p>Thanks for your help !</p>