using Set in a Svelte Custom Store with multiple variables

Question

when I use the update method, everything works fine but im trying to understand the set method for when a store is like this. What is the correct way?

export const todoStore = (() => {
    const { subscribe, update, set } = writable({
        allTask: [],
        isLoading: false,
    });

    return {
        subscribe,
        update,
        set,

        get: async () => {
            try {
                let { data, error } = await supabase.from('list').select('*');

                // method 1 using update words
                 update((state) => {
                     state.allTask = data;
                     return state;
                 });

                // method 2 using set doesn't work
                todoStore.set({
                    allTask: data
                });

                if (error) throw error;
            } catch (e) {
                console.log(e.message);
            }
        }
    };
})();

Answer 1

Like with update() call set() directly - with this you call the destructured methods from the writable store at the beginning const { subscribe, update, set } = writable(...)

On the return object this

return {
        subscribe,
        update,
        set,
        ...
}

is a shorthand for this

return {
        subscribe: subscribe,
        update: update,
        set: set,
        ...
}

while the values are references to the same destructured methods, so they can be called from outside on the store with todoStore.set() / todoStore.update()
If you want to prevent that the store is changed from the outside, you can remove update and set from the return object and only call them from inside the store scope