node_redis: is SMEMBERS blocking?

Under Redis's SCAN documentation, it mentions this about SMEMBERS:

However while blocking commands like SMEMBERS are able to provide all the elements that are part of a Set in a given moment, The SCAN family of commands only offer limited guarantees about the returned elements since the collection that we incrementally iterate can change during the iteration process.

Surprisingly, I can't find any additional information about how SMEMBERS is blocking and when to avoid using it. If SMEMBERS is a blocking call, is it safe to use in node_redis or will blocking Redis end up blocking Node's thread as well?

Slightly related, if SSCAN is the best practice instead of calling SMEMBERS, is there an equivalent SCAN call for SINTER?

Thanks in advance