The server node.js updates data every 0.5 seconds. The client has to poll the server and fetch new data using RxJS. I have made the client to poll server, the requests are made but I cant read the response from the server. I think that the state is not updated due to poll_server returning timer.pipe() or the reducer is creating a wrong state. I came to this from my teacher's template, so why the dispatcher would return an Observable?

model.js

export function init_state(warnings) {
    return {
        warnings,
        accept: ({ visit_site }) => { if (visit_site) return visit_site(warnings) }
    }
}

dispatcher.js

import { from, of, timer } from 'rxjs'
import { concatMap, map } from 'rxjs/operators'
import { FRONT_PAGE } from './constants'

const poll_server = url => {
    return timer(0, 3000)
        .pipe(concatMap(() => from(fetch(url))
            .pipe(map(response => response.json())))
        )
}

export const server_dispatch = action => {
    switch (action.type) {
        case FRONT_PAGE: {
            const res = poll_server('http://localhost:8080/warnings')
            console.log(res)
            return res
        }
        default:
            return of(action)
    }
}

reducer.js

export function reduce(state, action) {
    switch (action.type) {
        case FRONT_PAGE:
            console.log(`REDUCER CALLED WITH ACTION ${FRONT_PAGE}`)
            return init_state(action)
        default:
            return state
    }
}