How to wait for burgers (response to http://jlongster.com/Two-Weird-Tricks-with-Redux)

toastSaga.js

function* displayer() {

    const MaxToasts = 3;
    const ToastDisplayTime = 4000;

    let pendingToasts = [];
    let activeToasts = [];


    function* displayToast(toast) {
        if ( activeToasts >= MaxToasts ) {
            throw new Error("can't display more than " + MaxToasts + " at the same time");
        }
        activeToasts = [...activeToasts,toast];
        yield put(events.toastDisplayed(toast));
        yield call(delay,ToastDisplayTime);
        yield put(events.toastHidden(toast));
        activeToasts = _.without(activeToasts,toast);
    }

    function* toastRequestsWatcher() {
        while ( true ) {
            const event = yield take(Names.TOAST_DISPLAY_REQUESTED);
            const newToast = event.data.toastData;
            pendingToasts = [...pendingToasts,newToast];
        }
    }

    function* toastScheduler() {
        while ( true ) {
            if ( activeToasts.length < MaxToasts && pendingToasts.length > 0 ) {
                const [firstToast,...remainingToasts] = pendingToasts;
                pendingToasts = remainingToasts;
                yield fork(displayToast,firstToast);
                // Add little delay so that 2 concurrent 2 toast requests aren't display at the same time
                yield call(delay,300);
            }
            else {
                yield call(delay,50);
            }
        }
    }

    yield [
        call(toastRequestsWatcher),
        call(toastScheduler)
    ]
}



export default function* toastSaga() {
    yield [
        call(watcher),
        call(displayer)
    ]
}

This is an example on how you can build a toast system, that shows toasts for 4 seconds, can queue them, and make sure that no more than 3 toasts get displayed at the same time.

See picture of it running in production at stample.co: http://i.snag.gy/0moO6.jpg

More complex rules can be built on top of that (like for example reducing the toast display time if a lot of toasts are waiting to be displayed...)

I guess this same kind of logic can be applied to waiting for burgers. Instead of having your own code asking to "eat burger" (command/imperative), you should only dispatch that a burger has been seen (event/has-happened), and let a saga decide when it's the appropriate time to eat that burger.

See also http://stackoverflow.com/a/34623840/82609