svelte-persistent

Demo: https://leodog896.github.io/svelte-persistent/

localStorage and sessionStorage writables for SvelteKit & Svelte. SSR safe.

npm i -D svelte-persistent

import { localStore, sessionStore } from 'svelte-persistent';

// store(key, default).
const local = localStore('content', 'local');
const session = sessionStore('content', 'session');

Or JSON objects

import { localStore } from 'svelte-persistent'; // or sessionStorage!

const objectStore = localStore('content', {
    foo: 'bar'
});

Why?

When calling localStorage.set("key", value), this is a browser call. SvelteKit uses SSR (server-side rendering) which doesn't allow DOM calls during the rendering process.

localStorage.set('hello', 'world'); // localStorage is not defined!

With this in mind, in order to use localStorage effectively, you need to run it using onMount.

import { onMount } from 'svelte';

onMount(() => {
    localStorage.set('hello', 'world'); // works!
});

But, then you run into two problems:

• you may want the data for SSR beforehand, so that way you have placeholder data before the page loads.
• localStorage doesn't act as a reactive store, and won't react to sets/gets

This library solves both problems with a simple to use svelte store around local OR session storage.