Svelte

You can use the built-in Vite virtual module virtual:pwa-register/svelte for Svelte which will return writable stores (Writable<boolean>) for offlineReady and needRefresh.

WARNING

You will need to add workbox-window as a dev dependency to your Vite project.

Type declarations

TIP

If your TypeScript build step or IDE complain about not being able to find modules or type definitions on imports, add the following to the compilerOptions.types array of your tsconfig.json:

{
  "compilerOptions": {
    "types": [
      "vite-plugin-pwa/client"
    ]
  }
}

Or you can add the following reference in any of your d.ts files (for example, in vite-env.d.ts or global.d.ts):

/// <reference types="vite-plugin-pwa/client" />

declare module 'virtual:pwa-register/svelte' {
  // @ts-expect-error ignore when svelte is not installed
  import type { Writable } from 'svelte/store'

  export interface RegisterSWOptions {
    immediate?: boolean
    onNeedRefresh?: () => void
    onOfflineReady?: () => void
    /**
     * Called only if `onRegisteredSW` is not provided.
     *
     * @deprecated Use `onRegisteredSW` instead.
     * @param registration The service worker registration if available.
     */
    onRegistered?: (registration: ServiceWorkerRegistration | undefined) => void
    /**
     * Called once the service worker is registered (requires version `0.12.8+`).
     *
     * @param swScriptUrl The service worker script url.
     * @param registration The service worker registration if available.
     */
    onRegisteredSW?: (swScriptUrl: string, registration: ServiceWorkerRegistration | undefined) => void
    onRegisterError?: (error: any) => void
  }

  export function useRegisterSW(options?: RegisterSWOptions): {
    needRefresh: Writable<boolean>
    offlineReady: Writable<boolean>
    updateServiceWorker: (reloadPage?: boolean) => Promise<void>
  }
}

Prompt for update

You can use this ReloadPrompt.svelte component:

ReloadPrompt.svelte

<script lang="ts">
  import { useRegisterSW } from 'virtual:pwa-register/svelte';

  const { offlineReady, needRefresh, updateServiceWorker } = useRegisterSW({
    onRegistered(swr) {
      console.log(`SW registered: ${swr}`);
    },
    onRegisterError(error) {
      console.log('SW registration error', error);
    }
  });

  function close() {
    offlineReady.set(false)
    needRefresh.set(false)
  }

  $: toast = $offlineReady || $needRefresh;
</script>

{#if toast}
  <div
    class="pwa-toast"
    role="alert"
  >
    <div class="message">
      {#if $offlineReady}
      <span>
        App ready to work offline
      </span>
      {:else}
      <span>
        New content available, click on reload button to update.
      </span>
      {/if}
    </div>
    {#if $needRefresh}
      <button on:click={() => updateServiceWorker(true)}>
        Reload
      </button>
    {/if}
    <button on:click={close}>
      Close
    </button>
  </div>
{/if}

<style>
    .pwa-toast {
        position: fixed;
        right: 0;
        bottom: 0;
        margin: 16px;
        padding: 12px;
        border: 1px solid #8885;
        border-radius: 4px;
        z-index: 1;
        text-align: left;
        box-shadow: 3px 4px 5px 0 #8885;
        background-color: white;
    }
    .pwa-toast .message {
        margin-bottom: 8px;
    }
    .pwa-toast button {
        border: 1px solid #8885;
        outline: none;
        margin-right: 5px;
        border-radius: 2px;
        padding: 3px 10px;
    }
</style>

Periodic SW Updates

As explained in Periodic Service Worker Updates, you can use this code to configure this behavior on your application with the virtual module virtual:pwa-register/svelte:

import { useRegisterSW } from 'virtual:pwa-register/svelte'

const intervalMS = 60 * 60 * 1000

const updateServiceWorker = useRegisterSW({
  onRegistered(r) {
    r && setInterval(() => {
      r.update()
    }, intervalMS)
  }
})

The interval must be in milliseconds, in the example above it is configured to check the service worker every hour.