What is a Progressive Web App?
Basically, a PWA is a website that can be saved on the user's device (desktop, tablet or smartphone) and thus feels and behaves much like a Native application: loading screen, removing the browser's interface clutter to enhance user focus, and, should the connection drop, it still displays (cached) content, enabling the user to continue working offline.
Why is it important?
It tends to boost user engagement: if Android's Chrome browser (not sure about other mobile browsers) detects that the website is a PWA, it prompts the user to save it on its device's homescreen using the icon of your choice.
Compared to a mobile application, it simplifies the end-user setup process, breaking free from app stores.
PWA are good for your client's business. Alibaba, the Chinese Amazon, notices a 48% increase in user engagement thanks to the browser's prompt to "install" the website (source).
This makes the effort totally worth fighting for!
This bounty is possible thanks to a technology called Service Workers that allows you to save static assets in the user system (html, css, javascript, json...), alongside a manifest.json that specifies how the website should behave as an installed application. Service workers can do much much more, like polling user actions while offline, and syncing them in the background when back online.
Examples
Famous PWAs are Slack, Spotify, Starbucks, the NY Times, and many more...
Here are a couple PWAs made by myself using the same technique described here.
- plancomptablebelge.be (a single-page website)
- mathr.app (a game to practice calculous, made using Sveltekit)
Setup
Turning a website into a PWA may sound complicated (Service workers whaaaat ?), but it's not that difficult. Follow my lead and you'll have one by the end of this article !
1. requirement: https instead of http
PWA only work on a website running on a secure domain (behind https:// instead of http://).
These are usually very hard to set up manually, but thanksfully, if you have your own server, you can use letsencrypt to make that super easy and automatic. And... FREE.
2. Tools
2.1 lighthouse test
- the lighthouse test is an automated test created and maintained by Google that test websites against three criteria : Progressive, Performance, Accessibility. It gives a score in percent for each, and advises on how to solve each issue. It's a great learning tool.
- realfavicongenerator.net
- the UpUp.js library
2.2 realfavicongenerator.net
realfavicongenerator.net takes care of the visual layer of your PWA. It generates the manifest.json file mentioned above, alongside all the versions of your icons necessary when saving the website onto any mobile device, and an html snippet to add to your page's <head> tag.
2.3 service workers, via upup.js
Service Workers is a javascript technology. I found it hard to grasp for my tired and impatient brain, but luckily, a smart girl from Germany pointed me to a javascript library by Tal Atler, that makes it über easy to make your website behave nicely when the connexion drops. danke schön, Ola Gasidlo !
Just do the quick UpUp tutorial and you're good to go.
2.4 The Manifest
Edit the manifest.json file that RFG generated for you. It should contain at minimum these entries: "scope", "start_url", "short_name", "display". Here is a working sample:
{
"name": "My PWA Sample App",
"short_name" : "PWA",
"start_url": "index.html?utm_source=homescreen",
"scope" : "./",
"icons": [
{
"src": "./android-chrome-192x192.png",
"sizes": "192x192",
"type": "image/png"
},
{
"src": "./android-chrome-512x512.png",
"sizes": "512x512",
"type": "image/png"
}
],
"theme_color": "#ffee00",
"background_color": "#ffee00",
"display": "standalone"
}
More information is available at developers.google.com.
3. Methodology
- Use Realfavicongenerator and generate the html and image code. Add them to your website code.
- Publish on your https domain.
- Do the lighthouse test.
- Analyse results.
- Fix each issue one by one.
- Go back to 3, rince and repeat.
- Iterate until you get as close to 100 everywhere, and 100 in "Progressive".
- Test on your mobile phone and see what happens. With chance, on Android you'll see a popup at the bottom, inviting you to save the website onto your phone homescreen!
Deeper into the rabbit hole...
Here is a sample PWA project I made using a Github Page, live coded for my juniors at BeCode : visit its Github Page with your mobile phone to test it. Visit its repository to inspect the code.
You can find all the information you need on PWA in this book:
.
That's it! Happy PWA-ing!
Your PWA is ready: how about you learn how to automate its deployment using Git ?
Top comments (31)
Hi Alexandre, thank you for the very helpful article. Having built many websites over the years I'm now looking into PWAs as a way of offering different builds for clients. This is a great step forward in that. Thanks again for sharing.
I share pretty much the same story ! Happy I could help a bit!
It's very helpful, thank you. Out of interest, was the WordPress PWA more difficult? I'm looking to build a PWA for Joomla
The hard point to solve for me was "what content should I show when there is not connection?" and once you have that figured out, it's just a matter of having WP make it available to the ServiceWorker.
Ok thanks. Something for me to think about
I'd like to translate the article dev.to/pixeline/the-easy-way-to-tu... into Japanese and publish on our tech blog techracho.bpsinc.jp/ for sharing it if you're OK.
I make sure to indicate the link to original, title, author name in the case.
Best regards,
Sure ! As long as you indicate the links and authorship, feel free to translate it into Japanese. "Aligato !"
Thank you for the permission! Sure I do.
I like that post. Mucho.
Just shared it with the colleague who wrote this one: PWA Example: Progressive Web App E-Commerce with GatsbyJS. 🤘
Been a year since you first wrote it. Anything you'd change?
Hi! Thank you. As a matter of fact, I 've kept updating it. Eventually, with a public repository of a PWA boilerplate.
Hey Alexandre.
Greate tutorial!
I'm the author of the 'Web Into App' (webintoapp.com). The WebIntoApp allows you to turn any website into a native App for Android and iOS. You can create a FREE or a Dedicated APP, online, within a minute.
Feel free to try it at: webintoapp.com
Hey! I have a website (for sexual education) and in some countries, mainly in South Africa, users take too much time loading the website, I don't know if I should make my website into a PWA or is it better only use AMP? for which kind of websites would you recommend to use PWA?
PWA is well suited for your use case, especially if the content does not change that often. I would stay away from AMP, honestly.
I agree with this picture, application should be set in one click to attrach more users. I have a nice article about web App and web site development difference designmodo.com/web-application-int...
Thank you, Alexandre, for wrapping up the topic of PWAs! I didn't know anything about
upup.js, so it was truly an insightful read.My pleasure. This library should definitely be more popular !
Hi,
I'm having website developed in codeigniter and having index.php in the root folder, so can I convert my website into PWA..
I'm trying to migrate it but it's giving an error..
Is there any problem with .php files in PWA
Hello!
The short answer is : no problem !
PWA is a frontend technology. PHP is a backend technology, so since CodeIgniter is a MVC framework, you should probably work on the Views to include the necessary javascript, manifest, ... files.
I'm currently in the process of creating a PWA with angular cli tools like @angular-cli/serviceworkers. Can anyone show me a direction towards it? A blog link or something like that? Angular4 and above, using the CLI.
Great information, thanks for this!