Methods

On

Register event handlers for specific events or globally.

Event-specific handler

Parameters:

• event: Event name to listen to
• handler: Function called when event occurs
• options.signal: AbortSignal to automatically remove handler

Returns: Unsubscribe function

Example:

const unsubscribe = emitter.on('userLogin', ({ userId }) => {
  console.log(`User ${userId} logged in`)
})

// Later remove the handler
unsubscribe()

Global handler

Parameters:

• globalEventHandler: Function called for all events
• options.signal: AbortSignal to automatically remove handler

Returns: Unsubscribe function

Example:

const unsubscribe = emitter.on(({ kind, payload }) => {
  console.log(`Event ${kind}:`, payload)
})

Once

Register a one-time event handler that automatically removes itself after execution.

Event-specific handler

Parameters:

• event: Event name to listen to
• handler: Function called once when event occurs
• options.signal: AbortSignal to automatically remove handler

Returns: Unsubscribe function

Example:

emitter.once('userLogin', ({ userId }) => {
  console.log(`First login for user ${userId}`)
})

Global handler

Parameters:

• globalEventHandler: Function called once for the next event
• options.signal: AbortSignal to automatically remove handler

Returns: Unsubscribe function

Next

Wait for the next occurrence of an event or any event.

Wait for specific event

Parameters:

• event: Event name to wait for
• options.timeout: Milliseconds to wait before rejecting

Returns: Promise that resolves with event payload

Example:

try {
  const loginData = await emitter.next('userLogin', { timeout: 5000 })
  console.log('Login occurred:', loginData)
} catch (error) {
  if (error instanceof EmitterTimeoutError) {
    console.log('No login within 5 seconds')
  }
}

Wait for any event

Parameters:

• options.timeout: Milliseconds to wait before rejecting

Returns: Promise that resolves with event info

Example:

const nextEvent = await emitter.next({ timeout: 10000 })
console.log(`Event ${nextEvent.kind} occurred:`, nextEvent.payload)

Emit

Trigger an event with optional payload.

Parameters:

• event: Event name to emit
• payload: Data to pass to event handlers

Example:

emitter.emit('userLogin', { userId: '123', timestamp: Date.now() })
emitter.emit('userLogout', { userId: '123' })

Off

Remove event handlers.

Remove specific handler

Parameters:

• event: Event name
• handler: Specific handler to remove

Example:

const handler = (data: any) => console.log(data)
emitter.on('userLogin', handler)
emitter.off('userLogin', handler)

Remove all handlers for event

Parameters:

• event: Event name to clear all handlers for

Example:

emitter.off('userLogin') // Removes all userLogin handlers

Remove global handler

Parameters:

• globalEventHandler: Global handler to remove

Example:

const globalHandler = ({ kind, payload }) => console.log(kind, payload)
emitter.on(globalHandler)
emitter.off(globalHandler)

Count

Get the number of registered handlers.

Count handlers for specific event

Parameters:

• event: Event name to count handlers for
• options.global: Include global handlers in count

Returns: Number of handlers

Example:

const eventCount = emitter.count('userLogin')
const totalCount = emitter.count('userLogin', { global: true })

Count global handlers

Returns: Number of global handlers

Example:

const globalCount = emitter.count()

Clear

Remove all event handlers and global handlers.

Example:

emitter.clear() // Removes all handlers

Set Options

Update emitter configuration after creation.

Parameters:

• options.broadcastChannel: Channel name for cross-tab communication

Example:

emitter.setOptions({ broadcastChannel: 'new-channel' })