Set
SCARD
Return how many members are in a set
await redis.sadd("key", "a", "b", "c");
const cardinality = await redis.scard("key");
console.log(cardinality); // 3
await redis.sadd("key", "a", "b", "c");
const cardinality = await redis.scard("key");
console.log(cardinality); // 3