You can use the JavaScript SDK to determine which group a user is assigned to by using the getExperiment
API (or getExperimentWithExposureLoggingDisabled
if you need to check without triggering an exposure that would enroll the user into the experiment).
If you are trying to determine if a user has been exposed in the past, our SDKs are not able to return that information. While the SDKs deterministically can return an allocation result that is stable for the user and experiment, they are not historically aware of evaluation results.
For more information, read how bucketing works in Statsig SDKs.
Alternatively, there is an API that returns this information in the form of a daily report. Our data pipelines are aware of historical user assignments, so you can download that information via the Daily Reports Console API endpoint.