awayback v4.1.2

A custom event system.

import awayback from 'awayback'
const events = awayback()

events.on('event', (data) => {
  console.log(data)
  // data
})

events.emit('event', 'data')

Installation

Install using NPM (or yarn):

$ npm i -g npm
$ npm i --save awayback

In JavaScript:

// Require awayback & create a new instance
import awayback from 'awayback'
const events = awayback()

API

awayback()

Require awayback & create a new instance.

import awayback from 'awayback'
const events = awayback()

.on(event, callback, options)

• event <String>
• callback <Function>
  • ...data <Any>
• options <Object>
  • predicate <Function>
    • ...data <Any>
    • event <String>
    • returns: Boolean <Boolean>
  • signal <AbortSignal>
  • isExecutingPrevious <Boolean>

The callback is executed each time the event is fired. The arguments from the emit function call are also exposed to the listener.

events.on('name', (data) => {
  // Event is fired, callback executed
  // Use transmitted data
  console.log(data)
})

If the predicate option is provided, the callback is only executed if the predicate function returns true.

events.on(
  'event',
  (data) => {
    // Event is fired, callback executed
    // Use transmitted data
    console.log(data)
  },
  {
    predicate: (data) => data[0] === 'some',
  }
)

events.emit('event', ['some', 'data'])
// OUTPUT: ['some', 'data']

If the signal option is provided, the listener can be aborted using an AbortController.

const controller = new AbortController()
const { signal } = controller

events.on(
  'event',
  (data) => {
    console.log(data)
    // OUTPUT: data
  },
  { signal }
)

events.emit('event', 'data')

// Abort the listener
controller.abort()

events.emit('event', 'more data')
// No output, listener has been aborted

The signal option allows for fine-grained control over event listeners, enabling you to cancel them when they are no longer needed.

If the argument isExecutingPrevious in options is set to true, the listener executes event calls from before the initialization of the listener.

// Fire event before the initialization of .on()
// This event call will also be executed
events.emit('event', 'before')

setTimeout(() => {
  events.on(
    'event',
    (data) => {
      console.log(data)
      // OUTPUT: before
      // OUTPUT: after
      // OUTPUT: another call
    },
    {
      isExecutingPrevious: true,
    }
  )

  evens.emit('event', 'after')
  events.emit('event', 'another call')
}, 1000)

.once(event, callback, options)

• event <String>
• callback <Function>
  • ...data <Any>
  • event <String>
• options <Object>
  • predicate <Function>
    • ...data <Any>
    • event <String>
    • returns: Boolean <Boolean>
  • signal <AbortSignal>
  • isExecutingPrevious <Boolean>

The callback is only executed once when the event is called first. The arguments from the emit function call are also exposed to the listener.

events.once('event', (data) => {
  // Event is fired, callback executed
  // Use transmitted data
  console.log(data)
  // OUTPUT: one
})

events.emit('event', 'one')
events.emit('event', 'two')

If the predicate option is provided, the callback is only executed if the predicate function returns true.

events.once(
  'event',
  (data) => {
    // Event is fired, callback executed
    // Use transmitted data
    console.log(data)
  },
  {
    predicate: (data) => data[0] === 'some',
  }
)

events.emit('event', ['some', 'data'])
// OUTPUT: ['some', 'data']

If the signal option is provided, the listener can be aborted using an AbortController.

const controller = new AbortController()
const { signal } = controller

events.on(
  'event',
  (data) => {
    console.log(data)
    // OUTPUT: data
  },
  { signal }
)

events.emit('event', 'data')

// Abort the listener
controller.abort()

events.emit('event', 'more data')
// No output, listener has been aborted

The signal option allows for fine-grained control over event listeners, enabling you to cancel them when they are no longer needed.

If the argument isExecutingPrevious in options is set to true, the listener executes event calls from before the initialization of the listener.

// Fire event before the initialization of .once()
// This event call will also be executed
events.emit('event', 'before')

setTimeout(() => {
  events.once(
    'event',
    (data) => {
      console.log(data)
      // OUTPUT: before
    },
    {
      isExecutingPrevious: true,
    }
  )
}, 1000)

.only(event, callback, options)

• event <String>
• callback <Function>
  • ...data <Any>
  • event <String>
• options <Object>
  • predicate <Function>
    • ...data <Any>
    • event <String>
    • returns: Boolean <Boolean>
  • signal <AbortSignal>
  • isExecutingPrevious <Boolean>

The callback is only executed if this callback is the first and only one to be called. The arguments from the emit function call are also exposed to the listener.

events.only('name', (data) => {
  // Event is fired, callback executed
  // Use transmitted data
  console.log(data)
})

events.on('event', () => {})

events.only('event', (data) => {
  // Event is fired, callback is not executed
  // because it's not the only event listener
  console.log(data)
})

events.emit('event', 'data')

If the predicate option is provided, the callback is only executed if the predicate function returns true.

events.only(
  'event',
  (data) => {
    // Event is fired, callback executed
    // Use transmitted data
    console.log(data)
  },
  {
    predicate: (data) => data[0] === 'some',
  }
)

events.emit('event', ['some', 'data'])
// OUTPUT: ['some', 'data']

If the signal option is provided, the listener can be aborted using an AbortController.

const controller = new AbortController()
const { signal } = controller

events.on(
  'event',
  (data) => {
    console.log(data)
    // OUTPUT: data
  },
  { signal }
)

events.emit('event', 'data')

// Abort the listener
controller.abort()

events.emit('event', 'more data')
// No output, listener has been aborted

The signal option allows for fine-grained control over event listeners, enabling you to cancel them when they are no longer needed.

If the argument isExecutingPrevious in options is set to true, the listener executes event calls from before the initialization of the listener.

// Fire event before the initialization of .only()
// This event call will also be executed
events.emit('event', 'before')

setTimeout(() => {
  events.only(
    'event',
    (data) => {
      console.log(data)
      // OUTPUT: before
    },
    {
      isExecutingPrevious: true,
    }
  )
}, 1000)

.emit(event, ...data)

• event <String>
• ...data <Any>

Events can be fired using the function fire. The first required argument is the name of the event, the second, optional one, is data that can be transmitted.

events.emit('name', 'data')

Multiple arguments

More than two arguments can be passed on.

// Listen to the events 'first' and 'second'
events.on('event', (...data) => {
  console.log(data)
  // OUTPUT: ['some', 'data']
})

events.emit('event', 'some', 'data')

.promise(event): Promise

• event <String>
• options <Object>
  • timeout <Number>
  • reject <Array>
  • predicate <Function>
    • ...data <Any>
    • event <String>
    • returns: Boolean <Boolean>
  • signal <AbortSignal>
  • isExecutingPrevious <Boolean>
• returns: Promise <Promise>

Returns a promise that resolves with the value of the current instance. This function is useful for converting callback-based code to promise-based code.

setTimeout(() => {
  // Fire event after 300ms
  events.emit('ready', ['some', 'data'])
}, 300)

const result = await events.promise('ready')

console.log(result)
// OUTPUT: ['some', 'data']

If the predicate option is provided, the promise will only be resolved if the predicate function returns true.

const result = await events
  .promise('ready', {
    predicate: (data) => data[0] === 'some',
  })
  .then((data) => {
    console.log(data)
    // OUTPUT: ['some', 'data']
  })

events.emit('ready', ['some', 'data'])

If the timeout option is provided, the promise will be rejected after the specified time.

const result = await events
  .promise('ready', {
    timeout: 100,
  })
  .catch(() => {
    console.log('timeout')
    // OUTPUT: timeout
  })

If the reject option is provided, the promise will be rejected as soon as one of the provided events is fired.

const result = await events
  .promise('ready', {
    reject: ['error'],
  })
  .catch(() => {
    console.log('error')
    // OUTPUT: error
  })

events.emit('error')

.remove(event, callback)

• event <String>
• callback <Function>
  • ...data <Any>
  • event <String>

Removes a listener from the event so that this is no longer executed when firing.

const handler = () => {}

events.on('event', handler)
events.remove('event', handler)

.destroy()

Iterates through all registered event listeners and removes them, effectively disabling any further event handling for the object.

events.destroy()

License

MIT License

Copyright (c) 2025 Luca Joos

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.