Svelte

This guide shows you how to deploy a Svelte application on Layer0.

Install Node.js and npm

Layer0 only supports Node.js version 14.x

If you do not have Node.js installed on your system, download and install it from the official Node.js v14.x downloads page. Select the download that matches your operating system and run the installer. Note that the installer for Node.js will also install npm.

Note that while you can use any version of Node.js >= 14 locally, your app will run in Node 14 when deployed to the Layer0 cloud. Therefore we highly suggest using Node 14 for all development.

Sign up for Layer0

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Install the Layer0 CLI

If you have not already done so, install the Layer0 CLI

npm i -g @layer0/cli

Create a new Svelte app

If you don't already have a Svelte app, create one by running the following:

npx degit sveltejs/template-webpack svelte-app
cd svelte-app
npm install

You can verify your app works by running it locally with:

npm run dev

Configuring your Svelte app for Layer0

Initialize your project

In the root directory of your project run layer0 init:

layer0 init

This will automatically update your package.json and add all of the required Layer0 dependencies and files to your project. These include:

• The @layer0/core package - Allows you to declare routes and deploy your application on Layer0
• The @layer0/prefetch package - Allows you to configure a service worker to prefetch and cache pages to improve browsing speed
• layer0.config.js - A configuration file for Layer0
• routes.js - A default routes file that sends all requests to Svelte.

Adding Layer0 Service Worker

To add service worker to your Svelte app, run the following in the root folder of your project:

npm i process register-service-worker workbox-webpack-plugin

Create service-worker.js at the root of your project with the following:

import { skipWaiting, clientsClaim } from 'workbox-core'
import { precacheAndRoute } from 'workbox-precaching'
import { Prefetcher } from '@layer0/prefetch/sw'

skipWaiting()
clientsClaim()
precacheAndRoute(self.__WB_MANIFEST || [])

new Prefetcher().route()

To register the service worker, first create registerServiceWorker.js in the src folder:

/* eslint-disable no-console */

import { register } from 'register-service-worker'

if (process.env.NODE_ENV === 'production') {
  register(`/service-worker.js`, {
    ready() {
      console.log(
        'App is being served from cache by a service worker.\n' +
          'For more details, visit https://goo.gl/AFskqB',
      )
    },
    registered() {
      console.log('Service worker has been registered.')
    },
    cached() {
      console.log('Content has been cached for offline use.')
    },
    updatefound() {
      console.log('New content is downloading.')
    },
    updated() {
      console.log('New content is available; please refresh.')
    },
    offline() {
      console.log('No internet connection found. App is running in offline mode.')
    },
    error(error) {
      console.error('Error during service worker registration:', error)
    },
  })
}

and to include the service worker in the app, edit main.js (in the src folder) as follows:

import './global.css'
import App from './App.svelte'
+ import './registerServiceWorker'

const app = new App({
  target: document.body,
  props: {
    name: 'world',
  },
})

export default app

Now, in webpack.config.js make the following additions:

+ const { InjectManifest } = require("workbox-webpack-plugin");
+ const webpack = require('webpack')

  plugins: [
    + new webpack.ProvidePlugin({
    +   process: 'process/browser',
    + }),
    + new InjectManifest({
    +   swSrc: "./service-worker.js",
    + })
  ]

Configure the routes

Next you'll need to configure Layer0 routing in the routes.js file. Replace the routes.js file that was created during layer0 init with the following:

const { Router } = require('@layer0/core/router')

module.exports = new Router()
  // Send requests to static assets in the build output folder `public`
  .static('public')

  // Send everything else to the App Shell
  .fallback(({ appShell }) => {
    appShell('public/index.html')
  })

The example above assumes you're using Svelte as a single page app. It routes the static assets (JavaScript, CSS, and Images) in the production build folder public and maps all other requests to the app shell in public/index.html.

Refer to the Routing guide for the full syntax of the routes.js file and how to configure it for your use case.

Run the Svelte app locally on Layer0

Create a production build of your app by running the following in your project's root directory:

npm run build

Run Layer0 on your local machine:

npm run layer0:dev

Load the site http://127.0.0.1:3000

Deploying

Create a production build of your app by running the following in your project's root directory:

npm run build

Next, deploy the build to Layer0 by running the layer0 deploy command:

layer0 deploy

Refer to the Deploying guide for more information on the deploy command and its options.