little-pubsub

Small publish & subscribe class

INSTALL

npm

npm i --save @vandeurenglenn/little-pubsub

USAGE

import PubSub from '@vandeurenglenn/little-pubsub'
const pubsub = new PubSub()

Breaking Changes

v1.5.0

subscribe[context] & unsubscribe[context] -> subscribe[options({keepValue, context})]

// before
pusbub.subscribe(topic, handler, context)

// now
pusbub.subscribe(topic, handler, { context })

Example

import PubSub from '@vandeurenglenn/little-pubsub'
const pubsub = new PubSub()

pubsub.subscribe('event', (value) => {
  console.log(value)
})

pubsub.publish('event', 'hello')
// always runs handler
// (can use to overide littlePubsub.verbose setting without changing the behavior of the rest)
pubsub.publishVerbose('event', 'hello')

pubsub.unsubscribe('event', (value) => {
  console.log(value)
})

pubsub.hasSubscribers('event')

await pubsub.once('event')

API

pubsub(verbose?)

verbose: when false only fires after value change (default: false)

const pubsub = new PubSub() // verbose defaults to false
const pubsub = new PubSub(true) // always trigger handlers

subscribe

name: name of the channel to subscribe to handler: method options: { context }

Subscribing to an event returns an unsubscribe function. If value already exists, handler is called immediately.

const unsubscribe = pubsub.subscribe('event-name', (data) => {
  console.log(data)
})

// Later: clean unsubscribe
unsubscribe()

unsubscribe

name: name of the channel to unsubscribe handler: method options: { context, keepValue }

pubsub.unsubscribe(
  'event-name',
  (data) => {
    console.log(data)
  },
  { keepValue: false } // default
)

publish

name: name of the channel to publish to handler: method verbose: boolean

pubsub.publish('event-name', 'data')

publish

name: name of the channel to publish to handler: method

pubsub.publishVerbose('event-name', 'data')

once

name: name of the channel to get the value from

pubsub.getValue('event-name')

once

name: name of the channel to publish to

await pubsub.once('event-name')

hasSubscribers

name: name of the channel to check

pubsub.hasSubscribers('event-name') // true or false

subscriberCount

name: name of the channel to count

pubsub.subscriberCount('event-name') // number of handlers

clear

Removes all subscribers and values.

pubsub.clear()