People living on the island Hvar speak quite a unique version of Croatian. The Venice influence is huge there, graveyard is filled with gravestones of 16th+ century elite.

I sometimes find them hard to understand due to heavy usage of words with Italian roots. But their grammar is equivalent to Croatian grammar.

They also use the word "čaj".

I'd say Croatian as a language was popular and was heavily used on coastal areas even before Italian influence, and after too.