Svelte Storable

Svelte Storable is an extention to the writable store that comes with svelte/store. The purpose of the package is to preserve the state of the store, even after refresh.

Svelte Store adds localStorage management to the store while, with 1 exception preserves the api.

Installation

Include with npm:

npm install svelte-storable

Include locally:

Download storable.js from this repository and include it in your project.

Documentation

Use the svelte writalbe doumentation as a companion to this documentation if you aren't comfortable with svelte stores.

Creating a Store

The api for svelte-storable matches almost identically to the writable from svelte/store. The key difference is that you need to provide a key to the storable. This key will be used when storing and retrieving the persisted data.

// store.js
import { storable } from 'svelte-storable';

                                ||
                                \/
export const count = storable('count', 0);

Using the Store

Now you can use the store with all your usual writable methods. Additionally, you have the detatch() method. This can be used to remove the data from localStorage so that the value will be fresh on refresh.

:warning: NB: If you update the value after detatch() it will be stored again.

<!-- App.svelte -->
<script>
    import { count } from './store';

    const increase  = () => count.update((value) => value + 1);
    const decrease  = () => count.update((value) => value - 1);
    const reset     = () => count.set(0);
    const detatch   = () => count.detatch();

</script>

<h1>{$count}</h1>
<button on:click={count.increase}>Increase Count</button>
<button on:click={count.decrease}>Decrese Count</button>
<button on:click={count.reset}>Reset</button>
<button on:click={count.detatch}>Detatch from Storage</button>

Subscribe

You can use the $ syntax like any other svelte store or do it manually with unsubscribe/subscribe.

const unsubscribe = count.subscribe(value => doSomething(value));

Custom Stores

With writable you can make custom stores. This functionallity also copies over to svelte-storable. Again, the key difference is that you need to provide a key. You can optionally take that key as a parameter to your createStore() function with a default value.

// store.js
import { storable } from 'svelte-storable';

const createCountStore = (key = 'count') => {
    const { subscribe, set, update, detatch } = storable(key, 0);

    return {
        subscribe,
        increase:   () => update((value) => value + 1),
	decrease:   () => update((value) => value - 1),
	reset:      () => set(0),
        detatch:    () => detatch()
    }
}

export const count = createCountStore('count');

:warning: NB: Remember to provide different keys to all the different instances of your custom store. If two or more stores have the same key, they will update each other.