express-feature-flags__route-example.js

app.get('/', function(req, res, next) {
  const isEnabled = req.optimizely.client.isFeatureEnabled(
    'hello_world',       // Feature key connecting feature to UI
    'user123',           // String ID used for random percentage-based rollout
    {
      customerId: 123,   // Attributes used for targeted audience-based rollout
      isVip: true,
    }
  );

  res.send('Optimizely Express Example: ' +  (isEnabled ? 'You got the hello world feature!' : 'Feature off.'))
});