Hi! We are trying to set up A/B testing using the hybrid ssr/client-side approach described here: https://docs.growthbook.io/lib/react#hybrid-ssr--client-side Question: The code example in the documentation linked above says that when using

gb.setAttributes

on the client side, to "use the same values as SSR when possible". We are using

id

for persistent targeting but we can't know it on the server side due to cache. If the client-side

id

attribute doesn't match server-side

id

, what would the impact be in this case? My guess is there could be a "flash" where the feature flag value changes from what the server-side (cached)

id

was bucketed into, to what the client side

id

gets bucketed into?

That's my assumption as well - the user may see content that isn't assigned to them for the short time their

id

attribute is not populated

Thanks, we are going to try it and see how it goes. A follow up question, if you don't mind: We are calling

loadFeatures

on the client side, but seeing some inconsistent results. In our local environment, the features are already loaded by default on the server side (which is good, prevents the flicker). But on our staging environment, the features are not loaded until we call

loadFeatures

on the client side and thus we are seeing a flicker. Any idea why that would be? Should we be calling

loadFeatures

on both the server side and client side?

It's strange that it works in local but not in staging. How are you instantiating your

GrowthBook

instance? (Assuming it's the same in either environment)

On the server side we don't explicitly create an instance, we call

getGrowthBookSSRData

(from the growthbook-react SDK) and pass it our context containing apiHost, clientKey, attributes.id and attributes.environment, all of which are the same between local and staging except for the attributes. Looking at the SDK code, I see that it internally creates an instance and attempts to load the features:

// Get features from API and targeting attributes during SSR
export async function getGrowthBookSSRData(
  context: Context
): Promise<GrowthBookSSRData> {
  // Server-side GrowthBook instance
  const gb = new GrowthBook({
    ...context,
  });

  // Load feature flags from network if needed
  if (context.clientKey) {
    await gb.loadFeatures();
  }

  const data: GrowthBookSSRData = {
    attributes: gb.getAttributes(),
    features: gb.getFeatures(),
  };
  gb.destroy();

  return data;
}

So now I'm thinking the

loadFeatures

request here is being blocked somehow in our staging server. I can look deeper into that, unless you have another idea? Would that

loadFeatures

result be logged anywhere that we could look into?

That's possible. You should be able to call

getFeatures

on the GB instance (or directly look into

gb._ctx.features

)

Yeah when I look into

gb._ctx.features

it's an empty object on the server side

The devs tell me unfortunately no, there's nothing surfaced at the moment

Okay thanks, we'll try that. Appreciate the help!