PubSub

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API

PubSub

Demo Usage:

const { PubSub } = require('@beardedtim/pubsub);

// emit is how we can observe the result of some action
// in a uniformed way throughout the system.
//
// Think of `emit` as the `resolve` of a promise,
// the callback of a, well, callback function
//
// This is how we emit changes inside of the PubSub
// system into the outer scope
const emit = (...args) => {
  console.log(...args);
}

// Each PubSub instance MUST have an emit 
// function passed to its constructor.
const pubsub = new PubSub(emit);

// We want to subscribe to some event in the future
// called 'EVENT_NAME', with default scope applied,
// and when that even happens, I want to emit whatever
// was passed with that event.
pubsub.subscribe('EVENT_NAME', ({ emit }, ...data) => emit(...data));

// At some point in the future we
// publish that event into our system
// and eventually our `emit` function
// gets called.
pubsub.publish('EVENT_NAME', 1, 2, 3);
// 1, 2, 3

API:

• constructor: (emit: fn [, id: str, scoped: bool]) => void

  • Emit: Function to emit from the system
  • ID: The ID of this instance. Falls back to a guid
  • Scoped: If we are going to scope our event names

• getEventName: (event: str, scoped: bool) => str

  • Returns an EventName based on scoped
  • Example:

      const unScopedName = pubsub.getEventName('event', false) // 'event'
      const scopedName = pubsub.getEventName('event', true) // '${pubsub._id}:event'

• subscribe: (event: str, fn: function, scoped: bool) => fn

  • Adds an event listener to passed event

    • Example:

      const handleInput = ({ emit, publish, subscribe }, input) => {
        const massagedInput = sanitizeInput(input);
        publish('SANATIZED_INPUT', massagedInput);
      }
    
      const respondToUser = ({ emit }, payload) =>
        emit({
          type: 'RETURN_TO_USER',
          payload
        });
    
      const handleSanatizedInput = ({ emit }, input) =>
        emit({
          type: 'UPDATE_FORM',
          payload: input,
        });
          
      pubsub.subscribe('USER_NAME_UPDATE', handleInput);
      pubsub.subscribe('SANATIZED_INPUT', handleSanatizedInput);

• publish: (event: str [, ...args: [*]]) => void

  • Publishes an event to the system
  • Example:

    pubsub.subscribe('GET_DB', handleDB);
      
    const asyncPublish = action => payload =>
      pubsub.publish(action, payload);
      
    findDB()
      .then(asyncPublish('GET_DB'));

• __id: str

  • The ID of the instance

• __emit: fn

  • The emit function passed to the constructor

• __isScoped: bool

  • The scoped value passed to the constructor

GUID

This is a straight copy/paste from [stackOverflow](// https://stackoverflow.com/a/105074/3902127)

  // guid: () -> String
  guid() // some random string

Running Local Example

$ git clone [repo]

$ cd [repo]

$ yarn

$ yarn example

This will start a WebSocket server at ./.env's SOCKET_PORT= value or default to port 5001. You can send it the message { "type": "GET" } and get a response eventually. I use wscat for testing.

You may also find a basic example here