Event bus for vue and reactivity system

vue-event-bus.ts

import { getCurrentScope, onScopeDispose } from "vue"

class EventBus<Events extends Record<string, unknown>> {
  private readonly store = new Map<keyof Events, Set<(param: any) =>void>>()

  constructor() {
    this.on = this.on.bind(this)
    this.off = this.off.bind(this)
    this.emit = this.emit.bind(this)
  }

  on<Name extends keyof Events>(name: Name, cb: (param: Events[Name]) => void): () => void {
    let smap = this.store.get(name)

    if (!smap) this.store.set(name, smap = new Set())

    smap.add(cb)

    const stop = () => void this.store.get(name)?.delete(cb)

    const scope = getCurrentScope()
    if (scope) onScopeDispose(() => stop)

    return stop
  }
  off<Name extends keyof Events>(name: Name, cb?: (param: Events[Name]) => void): void {
    if (cb)
    this.store.get(name)?.delete(cb)
    else
    this.store.delete(name)
  }
  emit<Name extends keyof Events>(name: Name, param: Events[Name]): void {
    this.store.get(name)?.forEach(cb => cb(param))
  }
}


export function defineBus<Events extends Record<string, unknown>>() {
  const bus = new EventBus<Events>()

  return () => bus
}


/**
* @Usage: 
* bus.ts:
* ```ts
* export default defineBus<{ hello: name }()
* ```
* main.ts
* import useBus from "./bus"
*
* const { on, off, emit } = useBus()
*/