Offline and PWA

---
pwa: true
---

pwa: true (or pwa: build) makes slide-ng build write manifest.webmanifest and sw.js, a small service worker that stores every file of the build the first time the deck is opened. It also draws install icons, 192 and 512 pixels plus a maskable 512, so the deck can be installed.

• The icon is public/icon.png, else public/icon.svg, else a local favicon file in public/, else a generated one: a dark square with the first letter of the title.
• Drawing the icons needs Chromium. Without one the build warns and goes on without icons.
• A label in the bottom right corner says "Available offline" once everything is stored, and "Offline" while the browser has no network.
• Serve it over HTTPS or localhost. Browsers only allow service workers there.
• A new build gets a new cache name, so visitors get the new version on their next visit.

The first visit must be online. A browser that has never opened the deck cannot get it without a network. For talks with no network, use an offline folder.