Hashing is a process of deriving a relatively small data block (hash) from a larger block in a way so that unique data blocks have unique hashes (though it cannot be guaranteed due to the possible hash collisions). Different hashing algorithms provide different collision resistance and different performance. MurmurHash2 is a hashing algorithm optimised for fast computation and can't provide best cryptographic strength, so it may be used in a non-security-critical solutions, such as sharding or load balancing.
Javascript code snippet is available below.