Test-drive progressive web app development

[masakudamatsu]

Lighthouse Report says:

Current page does not respond with a 200 when offline

If you're building a Progressive Web App, consider using a service worker so that your app can work offline.

• https://web.dev/works-offline/?utm_source=lighthouse&utm_medium=lr

start_url does not respond with a 200 when offline

The start_url did respond, but not via a service worker.
A service worker enables your web app to be reliable in unpredictable network conditions.

• https://web.dev/offline-start-url/?utm_source=lighthouse&utm_medium=lr

Does not register a service worker that controls page and start_url

The service worker is the technology that enables your app to use many Progressive Web App features, such as offline, add to homescreen, and push notifications.

• https://web.dev/service-worker/?utm_source=lighthouse&utm_medium=lr

Manifest doesn't have a maskable icon

A maskable icon ensures that the image fills the entire shape without being letterboxed when installing the app on a device.

• https://web.dev/maskable-icon-audit/?utm_source=lighthouse&utm_medium=lr