How to Build SPAs With Svelte Stores

Single Page Applications (SPAs) have gained immense popularity due to their ability to provide a seamless user experience, resembling a desktop application. Svelte, a modern JavaScript framework, offers a unique approach to building these applications efficiently and effectively. One of the key features in Svelte is its store system, which simplifies state management in SPAs. This article will guide you through the process of building an SPA using Svelte stores.

Understanding Svelte Stores

Svelte stores provide a reactive mechanism for managing state across your application. There are three primary types of stores: writable, readable, and derived. Here's a brief overview:

Writable Stores: Used for storing mutable state. They can be updated and read by any component in the application.
Readable Stores: For state that doesn't need to be modified. They can only be subscribed to but not changed directly.
Derived Stores: Create a store based on one or more other stores, allowing you to compute values dynamically.

Setting Up Your Svelte SPA

To build a Single Page Application with Svelte, start by setting up your project using the official Svelte template. Use the following command to create a new Svelte project:

npx degit sveltejs/template my-svelte-app

Next, navigate into your project directory:

cd my-svelte-app

And install the required dependencies:

npm install

Creating a Svelte Store

After your project is set up, you can create a store. Start by creating a new file named store.js in the src directory:

touch src/store.js

In this file, you can create a writable store using Svelte's built-in `writable` function:

import { writable } from 'svelte/store';
export const count = writable(0);

This store will hold a simple counter value that can be updated throughout your application.

Using the Store in Components

To utilize the store in your components, simply import it and subscribe to its value. Here’s how to do it in a component, for instance, Counter.svelte:

<script>
    import { count } from './store.js';
</script>
<h1>Count: {$count}</h1>
<button on:click={() => count.update(n => n + 1)}>Increment</button>
<button on:click={() => count.set(0)}>Reset</button>

In this component, the count value is displayed, and users can increment or reset the counter. The {$count} syntax is a Svelte shorthand that allows you to access the current value of the store.

Building More Complex SPAs

As your application grows, you might want to involve multiple stores or derived stores. Here's a quick example of using a derived store:

import { writable, derived } from 'svelte/store';
export const count = writable(0);
export const doubleCount = derived(count, $count => $count * 2);

The doubleCount store creates a reactive value that always doubles the value of the count store. You can use it similarly in your components:

<h1>Double Count: {$doubleCount}</h1>

Routing in SPAs

Svelte does not come with built-in routing, but you can easily use a library like svelte-routing to create a multi-page experience within your SPA while still benefiting from the reactive nature of Svelte stores:

npm install svelte-routing

Once installed, you can set up your routes in the main application file, App.svelte:

<script>
    import { Router, Route, Link } from 'svelte-routing';
    import Counter from './Counter.svelte

How to Build SPAs With Svelte Stores