chore(clerk-js,shared): Improve createEventBus and move it to shared

[panteliselef]

Description

Extract createEventBus changes from #5476.

New APIs

• onBefore() is triggered after .emit() but its listeners are executed before the listeners of on().
• offBefore() unregisters onBefore
• internal.retrieveListeners() useful of lopping through listeners and attaching them to a new event bus instance. Exactly what we need when "hydrating" in isomorphic clerk

Replaced APIs

- dispatch
+ emit

Example

// Create a type-safe event bus
const bus = createEventBus<{
  'user:login': { id: string };
  'error': Error;
}>();

// Subscribe to events
const onLogin = ({ id }: { id: string }) => console.log('User logged in:', id);
bus.on('user:login', onLogin);

// Subscribe with priority (runs before regular handlers)
bus.onBefore('error', (error) => console.error('Error occurred:', error));

// Emit events
bus.emit('user:login', { id: 'user_123' });

// Unsubscribe specific handler
bus.off('user:login', onLogin);

// Unsubscribe all handlers
bus.off('error');

Checklist

• pnpm test runs as expected.
• pnpm build runs as expected.
• (If applicable) JSDoc comments have been added or updated for any package exports
• (If applicable) Documentation has been updated

Type of change

• 🐛 Bug fix
• 🌟 New feature
• 🔨 Breaking change
• 📖 Refactoring / dependency upgrade / documentation
• other:

[changeset-bot]

🦋 Changeset detected

Latest commit: c9167b8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 19 packages

Name	Type
@clerk/clerk-js	Patch
@clerk/shared	Minor
@clerk/chrome-extension	Patch
@clerk/clerk-expo	Patch
@clerk/agent-toolkit	Patch
@clerk/astro	Patch
@clerk/backend	Patch
@clerk/elements	Patch
@clerk/expo-passkeys	Patch
@clerk/express	Patch
@clerk/fastify	Patch
@clerk/nextjs	Patch
@clerk/nuxt	Patch
@clerk/react-router	Patch
@clerk/clerk-react	Patch
@clerk/remix	Patch
@clerk/tanstack-react-start	Patch
@clerk/testing	Patch
@clerk/vue	Patch

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Name	Status	Preview	Comments	Updated (UTC)
clerk-js-sandbox	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Apr 9, 2025 1:55pm

[brkalow]

❓ Why does this need to be public now?

[panteliselef]

In Clerk.status, isomorphic Clerk also uses an event bus until clerk-js hydrates.

[nikosdouvlis]

Not a fan of the naming here, I read it as "on 'before' event". How about preOn or similar?

[panteliselef]

I am not a fan of the current name either. How about prioritizedOn/Off ?

[jacekradko]

Could this just be an option that is set on the regular on and off methods?

[panteliselef]

Absolutely, and I tried that, it would make it go over 400bytes, and i decided to revert it. Do you feel strongly for about it ?

[panteliselef]

@jacekradko Keep in mind this will still be internal, it's just exported by shared.

Developers doing clerk.on() will not be able to do clerk. prioritizedOn()

[jacekradko]

@panteliselef I don't think it's too problematic, just a a larger API surface. We can always revisit in the future