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@xdn/prefetch - v1.43.6

XDN Prefetch

Prefetching library for the Moovweb XDN, infrastructure to run your big, dynamic website frontend and make it load in less than one second.

The @xdn/prefetch package makes it easy to prefetch dynamic content cached at the network edge and store it in the browser's service worker cache.

Caching Routes

To make a response prefetchable, it needs to cache the response both at the edge and in the service worker. You can do this using cache:

// routes.js
import { Router } from '@xdn/core/router'

new Router()
  .match('/some/path', ({ cache }) => {
      edge: {
        maxAgeSeconds: 60 * 60 * 24 // one day
      browser: {
        serviceWorkerSeconds: 60 * 60 // one hour

Prefetching Content

To prefetch a URL, call the following from JavaScript running in the browser window:

import { prefetch } from '@xdn/prefetch/window'


This will send a request with the following header:

  • x-xdn-prefetch: 1

To minimize the load on your origin servers, the XDN will only serve prefetch requests from the edge cache. If a prefetch request cannot be fulfilled from the edge cache, the XDN will respond with http status 412 PRECONDITION FAILED.

Configuring your Service Worker using Workbox

We recommend using Workbox's InjectManifest webpack plugin to create your service worker. To enable prefetching, simply create an instance of Prefetcher and call its route() method. Here's an example service worker:

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

precacheAndRoute(self.__WB_MANIFEST || [])

new Prefetcher().route()

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