Abstract

This module provides a class to manage callbacks . Use it in Classes to support setting callbacks .

Contents

• Meta
• Class Callbacks
  • Parameters
  • Methods
    • hasCallback
    • invokeCallback
    • invokeCallbackAsync
    • on

Meta

| | | | --- | --- | | File | callbacks.js | | Abstract | This module provides a class to manage callbacks . Use it in Classes to support setting callbacks . | | Author | Volker Böhm | | Copyright | Copyright ( c ) 2020 Volker Böhm | | License | This software is licensed under the GNU LESSER GENERAL PUBLIC LICENSE Version 3 . It is furnished "as is" , without any support , and with no warranty , express or implied , as to its usefulness for any purpose . |

Class Callbacks

new Callbacks(supportedEvents)

Creates a callback manager to manage callbacks and safely call them

Example

callbacks = new Callbacks(['publish'])
// register a callback
callbacks.on('publish', (param) => { console.log('called publish with ' + param) })
// invoke a callback
callbacks.invokeCallback('publish', 'a parameter')

Callbacks Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | supportedEvents | Array.<string> | Names of supported callbacks ( if undefined or null , all callbacks are allowed ) . Use this to prevent a user from registering callbacks with "on" that are not used by your class . | |

Callbacks Methods

hasCallback

hasCallback (name) => {boolean}

Checks , if a callback is registered

hasCallback Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | name | string | name of the callback to look for | |

hasCallback returns

| Type | Description | | ---- | ----------- | | boolean | true , if the callback is registered |

invokeCallback

invokeCallback (event, param) => {any}

Calles a callback stored to an event , if registered

invokeCallback Parameters

| Name | Type | Attribute | Description | | ---------- | ------------ | ------------ | ----------------- | | event | string | | event name ( not case sensitive ) for callback | | | param | any | repeatable | parameters to pass to the callback | |

invokeCallback returns

| Type | Description | | ---- | ----------- | | any | the result of the callback or null , if the callback is not defined |

invokeCallbackAsync

async invokeCallbackAsync (event, param) => {any}

Callcs a callback stored to an event , if registered . It is the async version

invokeCallbackAsync Parameters

| Name | Type | Attribute | Description | | ---------- | ------------ | ------------ | ----------------- | | event | string | | event name ( not case sensitive ) for callback | | | param | any | repeatable | parameters to pass to the callback | |

invokeCallbackAsync returns

| Type | Description | | ---- | ----------- | | any | the result of the callback or null , if the callback is not defined |

on

on (event, callback)

Sets a callback .

on Parameters

| Name | Type | Description | | ---------- | ------------ | ----------------- | | event | string | event name ( not case sensitive ) for the callback | | | callback | function | function ( . . . parameter ) | |

on throws

| Type | Description | | ---- | ----------- | | Error | if the event is not supported | | Error | if the callback is not 'function' |