@dloizides/event-landing-kit

Framework-free toolkit for single-page event landing sites (dance socials, congresses, one-off parties). Extracted from the hand-written Kizomba Union CY and United by Salsa sites, which duplicated the same four pieces of logic with a copy-paste bug between them.

It ships browser IIFE bundles meant to be vendored into static sites that have no build step (<script src> + importScripts), plus CJS/ESM for anyone who does build. Zero runtime dependencies.

What's in it

| Piece | API | Replaces | |---|---|---| | Service-worker core | self.EventSW.register({...}) | the per-site sw.js (network-first HTML, SWR assets, gated live paths) | | Live registration stats | EventLandingKit.initLedgerStats({...}) | the ledger.json → counts widget | | Deadline countdown | EventLandingKit.initCountdown({...}) | the register ↔ "pay at the door" swap + countdown | | WhatsApp deep link | EventLandingKit.buildWhatsAppUrl(phone, lines) | the wa.me URL builder in the register form |

The registration form itself stays per-site (each event has its own passes / add-ons / pricing); only the WhatsApp-link builder is shared.

Vendoring into a build-step-less static site

Copy the two IIFE files from dist/ into the site (e.g. assets/js/):

dist/event-landing-kit.global.js  → assets/js/event-landing-kit.js
dist/event-sw-core.global.js      → assets/js/event-sw-core.js

Page kit

<script src="/assets/js/event-landing-kit.js"></script>
<script>
  EventLandingKit.initLedgerStats();             // defaults: /ledger/ledger.json, threshold 100
  EventLandingKit.initCountdown({
    deadlineMs: new Date('2026-05-16T13:00:00+03:00').getTime(),
    strings: {
      bookSubOpen:   'Reserve your pass, then pay via Revolut.',
      bookSubClosed: 'Online payments closed — pay cash at the door.',
    },
  });
  // In the register form's submit handler:
  const url = EventLandingKit.buildWhatsAppUrl('35796650527', lines);
</script>

Both initLedgerStats and initCountdown default to the canonical element IDs (reg-stats, reg-stat-total, register-countdown, cd-days, book-sub, …) and no-op safely when an element is missing — so partial pages just work.

Service worker (sw.js)

importScripts('/assets/js/event-sw-core.js');
self.EventSW.register({
  cacheName: 'kucy-v185',     // bump on each asset change
  cachePrefix: 'kucy-',       // cleanup deletes ONLY this site's caches
  precache: ['/', '/index.html', '/manifest.webmanifest', '/assets/logo/icon-192.png'],
  gatedPaths: ['/ledger/', '/door/', '/ticket/', '/media/', '/mediaTicket/', '/dj/'],
  // fallbackDocument defaults to '/index.html'
});

cachePrefix fixes the original fork bug: each site must clean up only its own caches. (The pre-extraction UBS worker still purged kucy- caches — a leftover from being copied off the KUCY worker.)

Behaviour notes

• Strategy is identical to the workers it replaces: HTML/navigation → network-first (cache fallback → fallback document); other same-origin GETs → stale-while-revalidate; cross-origin + gated live paths → pass-through.
• The install step per-item-catches precache failures so one renamed/missing asset doesn't fail the whole install. (The extracted core does this silently — the original logged a console.warn.)
• initLedgerStats exposes only aggregate counts (total / male / female / other / not-specified, paid vs expected) and reveals the card only past the threshold. It never throws — on any error the stats just stay hidden.
• initCountdown is pure client-side: every visit re-checks the clock, so no redeploy is needed at the cutover. It returns a controller with stop().

Development

npm install
npm run lint && npm run typecheck && npm test   # 100% coverage gate
npm run build                                    # dist/ (cjs + esm + iife + d.ts)

MIT © dloizides