Zephyr Events – A 2KB TypeScript event emitter that's race-condition safe

I built a tiny event emitter that fixes a bug most people don't know they have: if a handler calls off() on itself during emit, the next handler gets skipped. EventEmitter3, Node's built-in EventEmitter, and mitt all have this problem.

Zephyr Events uses snapshot-based iteration so handlers can subscribe, unsubscribe, or clear listeners mid-emit without side effects. If you don't need that safety, there's a zephyrEventsFast mode that's up to 82% faster.

1.9KB, zero dependencies, tree-shakeable

Full TypeScript generics with strict handler signatures

Wildcard listeners, shared handler maps, unsubscribe functions

ESM, CommonJS, and UMD builds

import zephyrEvents from 'zephyr-events';



type Events = {

  'user:login': { id: number; name: string }

  'error': Error

}



const emitter = zephyrEvents<Events>();

const unsub = emitter.on('user:login', (user) => {

  console.log(`Welcome, ${user.name}`);

});

emitter.emit('user:login', { id: 1, name: 'Alice' });

unsub();

https://www.npmjs.com/package/zephyr-events

Would love feedback, especially on the API design and whether the safe/fast split makes sense as a default.