communication-bus/src/subscribers.js

Publisher subscriber library for communication in JS across components

import Publisher from "./publisher";

const Subscribers = {
    idOffset: 0,
    order: [],
    callbacks: {}
}

const deregister = (id)=>{
    if(!id) throw new Error("id is required");
    if(Subscribers.order.indexOf(id) !== -1){
        Subscribers.order = Subscribers.order.filter((subscriberId)=>id!==subscriberId);
        delete Subscribers.callbacks[id]
        return true
    }
    return false
}

const register = (callback, offset=0)=>{
    if(typeof callback !== "function") throw new Error("Callback function is required"); 
    const newSubscriberId = ++Subscribers.idOffset;
    Subscribers.order.push(newSubscriberId);
    Subscribers.callbacks[newSubscriberId] = callback;
    if(offset > 0){
        Publisher.rePublishEventForSubscriber(newSubscriberId, offset)
    }
    return deregister.bind(null,newSubscriberId);
}



const getOrderedSubscribers = ()=>{
    return Subscribers.order.map((id)=>{
        return Subscribers.callbacks[id];
    })
}

const getSubscriberById = (id)=>{
    if(!id) throw new Error("id is required");
    return Subscribers.callbacks[id]
}


export default {
    register,
    deregister,
    getSubscriberById,
    getOrderedSubscribers
}