Diablo 2 - Does Dracul's Grasp cast life tap on Javazon?

Yes throwing a javelin counts as "striking". These gloves are just poorly worded. Basically it means using any "attack" and not a "spell".

Sorce spells like Nova are NOT attacks, Assassin traps are NOT attacks, for example.

For your question with javazons, I included two examples to help with judging what is an attack and what is not.

Lightning strike and charged strike will proc because it hits with the javelin (the splits from lightning strike do not count because they count as a spell and not an attack), while a skill like poison javelin will NOT work, because it just leaves a trail of poison and doesn't hit.

Open wounds also counts towards this same rule.

According to https://www.diabloii.net/forums/threads/difference-between-striking-and-attack.314113/

Striking is when you hit (ie. you don't miss)