how do i get a hex key from an npub nip05 id?

// Find the first event from @jack, and zap it.
const jackHexPubKey = "82341f882b6eabcd2ba7f1ef90aad961cf074af15b9ef44a09f9d2a8fbfbe6a2";
const event = await ndk.fetchEvent({ authors: [jackHexPubKey] });
await event.zap(1337, "Zapping your post!");