React-Redux Component not showing new props in store

Question

I am attempting to create my own alert component using react (also in this case, Bootstrap v4). Basically, if something happens which the user needs to be notified of, create a message, put it in the store and have react render the alert. I know what I am doing should be possible, however I am new enough to react that there is something I am missing/don't understand about how react works which is causing no alerts to be displayed.

Firstly, I alerts to be available to all other components, so I put it in my app.js:

import React from 'react';
import ReactDOM from 'react-dom';
import { Provider } from 'react-redux';
import { PersistGate } from 'redux-persist/integration/react';
import AppRouter from './routers/AppRouter';
import configureStore from './store/configureStore';

import Alerts from './components/controls/Alerts';

const { store, persistor } = configureStore();

const jsx = (
    <Provider store={store}>
        <PersistGate loading={null} persistor={persistor}>
            <Alerts />
            <AppRouter />
        </PersistGate>
    </Provider>
);

ReactDOM.render(jsx, document.getElementById('root'));

Next are the components for Alerts. First the actions:

// DISPLAY_ALERT
export const displayAlert = (message, severity) => ({
    type: 'DISPLAY_ALERT',
    message: message,
    severity: severity
});

// DISMISS_ALERT
export const dismissAlert = (id) => ({
    type: 'DISMISS_ALERT',
    id: id
});

The reducer:

const alertsDefaultState = [];

const alertNotify = (state, action) => {
    let queue = state;

    if (!queue || !Array.isArray(queue))
        queue = [];

    let newAlert = {
        id: getUniqueId(),
        message: action.message,
        severity: action.severity
    };

    queue.push(newAlert);

    return queue;
};

const alertDismiss = (state, action) => {
    const newQueue = state.filter((element) => element.id !== action.id);

    return newQueue;
};

const getUniqueId = () => {
    return (Date.now().toString(36) + Math.random().toString(36).substr(2, 5)).toUpperCase();
};

export default (state = alertsDefaultState, action) => {
    switch (action.type) {
        case 'DISPLAY_ALERT':
            return alertNotify(state, action);
        case 'DISMISS_ALERT':
            return alertDismiss(state, action);
        case 'LOG_OUT_OF_API':
            return [];
        default:
            return state;
    }
};

The store:

import { createStore, combineReducers } from 'redux';
import { persistStore, persistReducer } from 'redux-persist';
import storage from 'redux-persist/lib/storage';
import alertsReducer from '../reducers/alerts';

export default () => {
    const persistConfig = {
        key: 'root',
        storage,
    };

    let reducers = combineReducers({
        // Other reducers
        alerts: alertsReducer
    });

    let store = createStore(
        persistReducer(persistConfig, reducers),
        window.__REDUX_DEVTOOLS_EXTENSION__ && window.__REDUX_DEVTOOLS_EXTENSION__()
    );

    let persistor = persistStore(store);

    return { store, persistor };
};

And finally the Alerts components:

import React from 'react';
import { connect } from 'react-redux';
import { dismissAlert } from '../../actions/alerts';

class Alerts extends React.Component {
    constructor(props) {
        super(props);
    }

    getAlerts = () => {
        if (!this.props.alerts || this.props.alerts.length === 0)
            return null;

        const alertFixed = {
            position:'fixed',
            top: '0px',
            left: '0px',
            width: '100%',
            zIndex: 9999,
            borderRadius: '0px'
        };

        return (
            <div style={alertFixed}>
                {
                    this.props.alerts.map((alert) => {
                        const alertClass = `alert alert-${alert.severity} alert-dismissible m-4`
                        setTimeout(() => {
                            this.props.dispatch(dismissAlert(alert.id));
                        }, 5000);
                        return (
                            <div key={alert.id} id={alert.id} className={alertClass} role="alert">
                                <button type="button" className="close" data-dismiss="alert" aria-label="Close">
                                    <span aria-hidden="true">&times;</span>
                                </button>
                                { alert.message }
                            </div>
                            );
                        }
                    )
                }
            </div>
        );
    }

    render() {
        return this.getAlerts()
    }
}

const mapStateToProps = (state) => {
    return {
        alerts: state.alerts
    }
};

export default connect(mapStateToProps)(Alerts);

One last thing, I have a const class for the types of alerts:

export default {
    Info: 'info',
    Success: 'success',
    Warning: 'warning',
    Error: 'danger',
};

If I run the above code and have something in the alerts store, then it will be rendered. However, if I add something to the store on an event, such as a button click, I can see the alert being added to the store, but the component won't add it to the DOM.

What am I missing?

EDIT:

Here is a code sandbox

Answer 1

Arrays are reference type in Javascript

In your

const alertNotify = (state, action) => {
    let queue = state;

    if (!queue || !Array.isArray(queue))
        queue = [];

    let newAlert = {
        id: getUniqueId(),
        message: action.message,
        severity: action.severity
    };

    queue.push(newAlert);

    return queue;
};

Instead of doing something like this

 let queue = state;

You need to make a copy of it (instead of referencing it) and then do

queue.push(newAlert);

i.e change your initial queue declaration to this (i am using spread operator to make copy of your passed state and then pushing newAlert in your queue

let queue = [...state];

Since your queue when returning, didn't had state in it

This condition was being fired

 if (!this.props.alerts || this.props.alerts.length === 0)