Is it possible to access Svelte store from external js files?

Question

I am wondering if i would be able to access my Svelte store values from a plain .js file.

I am trying to write functions returning a dynamic value based on a store value, to import them in any component. But in a plain .js file I can't just access the store value with the $ sign..

Quick exemple of a basic function that uses a store value and could be used on multiple components:

//in .svelte

function add() {
    $counter = $counter + 1;
 }

EDIT: rephrasing a bit

EDIT: Found a solution but i don't really know if it's really optimized..

//in .js file

import { get } from "svelte/store";
import { counter } from "./stores";

export function add() {
    var counterRef = get(counter);
    counter.set(counterRef + 1);
}

Answer 1

Yes, absolutely.

For one thing, the store API is very simple and nothing prevents you from subscribing to the store yourself to know the value:

import myStore from './stores'

myStore.subscribe(value => {
  // do something with the new value
  // you could store it for future reference...
})

And, if you just want to know the current value, Svelte has a helper for that, the get function:

import { get } from 'svelte/store';

import myStore from './stores'

const value = get(myStore);

Answer 2

In addition to rixo's answer, a better way to implement add is to use the store's update method:

import { counter } from "./stores";

export function add() {
    counter.update(n => n + 1);
}

You could also create a custom store that implemented that logic.