Making your IONIC app a PWA
The two main requirements of a PWA are a Service Worker and a Web Manifest. While it’s possible to add both of these to an app manually, the Angular team has an @angular/pwa
the package that can be used to automate this.
The @angular/pwa
the package will automatically add a service worker and an app manifest to the app. To add this package to the app, run:
ng add @angular/pwa
Once this package has been added run ionic build --prod
and the www
the directory will be ready to deploy as a PWA.
Service Worker configuration
After @angular/pwa
has been added, a new ngsw-config.json
the file will be created at the root of the project. This file is responsible for configuring how Angular’s service worker mechanism will handle caching assets. By default, the following will be provided:
{
"$schema": "./node_modules/@angular/service-worker/config/schema.json",
"index": "/index.html",
"assetGroups": [
{
"name": "app",
"installMode": "prefetch",
"resources": {
"files": [
"/favicon.ico",
"/index.html",
"/*.css",
"/*.js"
]
}
}, {
"name": "assets",
"installMode": "lazy",
"updateMode": "prefetch",
"resources": {
"files": [
"/assets/**",
"/*.(eot|svg|cur|jpg|png|webp|gif|otf|ttf|woff|woff2|ani)"
]
}
}
]
}
There are two sections here, one for app-specific resources (JS, CSS, HTML) and assets the app will load on demand. Depending on your app, these options can be customized. For a more detailed guide, read the official guide from the Angular Team.
Deploying on Firebase
Firebase Hosting provides many benefits for Progressive Web Apps, including fast response times thanks to CDNs, HTTPS enabled by default, and support for HTTP2 push.
First, if not already available, create the project in Firebase.
Next, in a Terminal, install the Firebase CLI:
$ npm install -g firebase-tools
With the Firebase CLI installed, run firebase init
within your Ionic project. The CLI prompts:
“Which Firebase CLI features do you want to set up for this folder?” Choose “Hosting: Configure and deploy Firebase Hosting sites.”
“Select a default Firebase project for this directory:” Choose the project you created on the Firebase website.
“What do you want to use as your public directory?” Enter “www”.
Note: Answering these next two questions will ensure that routing, hard reload, and deep linking work in the app:
Configure as a single-page app (rewrite all URLs to /index.html)?” Enter “Yes”.
“File www/index.html already exists. Overwrite?” Enter “No”.
A firebase.json
the config file is generated, configuring the app for deployment.
The last thing needed is to make sure caching headers are being set correctly. To do this, add a headers
snippet to the firebase.json
file. The complete firebase.json
looks like this:
{
"hosting": {
"public": "www",
"ignore": [
"firebase.json",
"**/.*",
"**/node_modules/**"
],
"rewrites": [
{
"source": "**",
"destination": "/index.html"
}
],
"headers": [
{
"source": "/build/app/**",
"headers": [
{
"key": "Cache-Control",
"value": "public, max-age=31536000"
}
]
},
{
"source": "ngsw-worker.js",
"headers": [
{
"key": "Cache-Control",
"value": "no-cache"
}
]
}
]
}
}
For more information about the firebase.json
properties, see the Firebase documentation.
Next, build an optimized version of the app by running:
$ ionic build --prod
Last, deploy the app by running:
$ firebase deploy
After this completes, the app will be live.
I have followed the following link to implement PWA in my IONIC app:
https://ionicframework.com/docs/angular/pwa