I have a svelte store that has the following code

import { writable } from "svelte/store";
import { onMount, onDestroy } from "svelte";

export const modalStore = () => {
    const { subscribe, update } = writable({
        showModal: false,
    });

    onMount(() => {
        window.addEventListener("keydown", handleKeyDown);
    });

    onDestroy(() => {
        window.removeEventListener("keydown", handleKeyDown);
    });

    const handleKeyDown = (e: KeyboardEvent) => {
        if (e.key === "Escape") {
            update(stateObj => ({...stateObj, showModal: false}));
        }
    }
    return  {
        subscribe,
        openModal: () => update(stateObj => ({ ...stateObj, modal: true })),
        closeModal: () => update(stateObj => ({ ...stateObj, modal: false })),
        handleKeyDown,

    }
}

Edit

I have accessed the store by the following code

let modalState = modalStore();

Then checked the state by $modalState and the accessed the function by modalStore.openModal();

It throws 500 error with - window is not defined

How can I solve it?

I have a svelte store that has the following code

import { writable } from "svelte/store";
import { onMount, onDestroy } from "svelte";

export const modalStore = () => {
    const { subscribe, update } = writable({
        showModal: false,
    });

    onMount(() => {
        window.addEventListener("keydown", handleKeyDown);
    });

    onDestroy(() => {
        window.removeEventListener("keydown", handleKeyDown);
    });

    const handleKeyDown = (e: KeyboardEvent) => {
        if (e.key === "Escape") {
            update(stateObj => ({...stateObj, showModal: false}));
        }
    }
    return  {
        subscribe,
        openModal: () => update(stateObj => ({ ...stateObj, modal: true })),
        closeModal: () => update(stateObj => ({ ...stateObj, modal: false })),
        handleKeyDown,

    }
}

Edit

I have accessed the store by the following code

let modalState = modalStore();

Then checked the state by $modalState and the accessed the function by modalStore.openModal();

It throws 500 error with - window is not defined

How can I solve it?

• javascript
• dom
• window
• svelte
• sveltekit

• 2 The problem has to be SSR. When using svelteKit, every ponent gets rendered on the server before being sent to the browser. The thing is, window is used inside of onMount so I think that shouldn't be the problem. Can you share maybe how you are using the store? – Odilf Commented Oct 26, 2022 at 10:19
• modalStore is exported, check whether openModal is being called anywhere outside of an onMount function? – Oscar Hermoso Commented Oct 26, 2022 at 10:20
• @OscarHermoso: I used the openModal function in the ponent in which the store (modalStore) was called. I have initiated the store by let modalState = modalStore(); and then accessed modalState.openModal – jeff Commented Oct 26, 2022 at 11:00
• 1 Just as you can add event listeners to any DOM element, you can add event listeners to the window object with <svelte:window>. Example: <svelte:window on:keydown={handleKeydown}/> – voscausa Commented Oct 26, 2022 at 12:17
• 1 @OscarHermoso Actually I was able to get it working my slightly modifying the onMount function (posted here ) – jeff Commented Oct 26, 2022 at 13:32

2 Answers 2

The problem is that onDestroy gets executed on the server. So instead of using onDestroy the function returned from onMount should be used.

Docs:

Out of onMount, beforeUpdate, afterUpdate and onDestroy, this is the only one that runs inside a server-side ponent.

export const modalStore = () => {
    const { subscribe, update } = writable({
        showModal: false,
    });

    onMount(() => {
        const handleKeyDown = (event: KeyboardEvent) => {
            if (event.key === "Escape") {
                update((storeObj) => {
                    storeObj.showModal = false;
                    return storeObj;
                });
            }
        };

        window.addEventListener("keydown", handleKeyDown);

        return () => {
            window.removeEventListener("keydown", handleKeyDown);
        };
    });

    const handleKeyDown = (e: KeyboardEvent) => {
        if (e.key === "Escape") {
            update(stateObj => ({...stateObj, showModal: false}));
        }
    }


    return  {
        subscribe,
        openModal: () => update(stateObj => ({ ...stateObj, showModal: true })),
        closeModal: () => update(stateObj => ({ ...stateObj, showModal: false })),
        handleKeyDown,
    }
}

I dont know how. But its working now without error