Turn Your Eleventy-powered Site into Offline-First Progressive Web Apps

     5 minutes to read
an event that happens approximately 66 million years ago, chromiumized

After mobile first, offline first and progressive web apps (PWA) are the current trend at the moment.
So, why not to make your eleventy's powered website works in offline too ?

Install PWA-plugin for eleventy

Let’s start by installing eleventy-plugin-pwa

$ npm install eleventy-plugin-pwa --save-dev

In this case, using plugin instead using workbox-cli or other interface like gulp/webpack are easier,
Especially when you're using the eleventy --serve to test and watch your changes, since this plugin will automatically follow and rebuild our service-worker too.

Adding it to Eleventy config file

As usual, we need to include the plugin in our .eleventy.js to enable it.

// .eleventy.js
const pluginPWA = require("eleventy-plugin-pwa");

module.exports = (eleventyConfig) => {
//...
eleventyConfig.addPlugin(pluginPWA, {
swDest: "./build/service-worker.js",
globDirectory: "./build",
clientsClaim: true,
skipWaiting: true
});
//...
};

Also you can use it without any configuration, which by default it will set the destination to ${eleventy.outputDir}/service-worker.js.

For more info about the options, you can read here :
https://developers.google.com/web/tools/workbox/modules/workbox-build#full_generatesw_config

manifest.json

To make it installable on mobile devices, we need to add ./manifest.json for it.

{
"name": "My Beautiful Website",
"short_name": "okitavera.me",
"icons": [
{
"src": "/assets/img/favicon/192.png",
"sizes": "192x192",
"type": "image/png"
},
{
"src": "/assets/img/favicon/512.png",
"sizes": "512x512",
"type": "image/png"
}
],
"theme_color": "#ec407a",
"background_color": "#ec407a",
"display": "standalone",
"start_url": "/"
}

copy ./manifest.json directly using addPassthroughCopy() (documentation)

module.exports = (eleventyConfig) => {
//...
eleventyConfig.addPassthroughCopy("manifest.json");
//...
};

Also don't forget to mention that file inside your header

<head>
...
<link rel="manifest" href="/manifest.json" />
...
</head>

Registering Service Worker

Now the tricky part is registering service worker.
Because we need our website updated everytime the we had a new content, we need to cache-bust the service worker file.

The simplest ways to do this is using eleventy's addFilter to append a new string everytime we run the eleventy to build our page.

// .eleventy.js
module.exports = (eleventyConfig) => {
//...
// append "?v=timestamp" to the end of str
eleventyConfig.addFilter("cacheBust", (str) => {
const dateNow = Date.now();
return str.concat(`?v=${dateNow}`);
});
//...
};

And finally, we put a simple javascript into our header/footer to register the service-worker.


<script>
if ("serviceWorker" in navigator) {
navigator.serviceWorker
.register("{{ '/service-worker.js' | cacheBust }}")
.then(function() {
console.log("ServiceWorker has been registered!");
})
.catch(console.error);
}
</script>

Final

Okay, it's time to test our 5 minutes work.

pwa-chrome-console

Lighthouse benchmark:
pwa-chrome-lighthouse


PWAeleventyJAMstacknodejswebdev
WRITTEN BY

Nanda Okitavera

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