Adapters

Three concrete Tracker implementations ship in @lernkit/tracker. Each fulfills the same interface; they differ only in what they do with the calls.

Adapter	Use case	Side effects
NoopAdapter	Static preview, tests	Nothing — methods resolve, state stays in memory
XapiStubAdapter	Dev, prototyping	Builds an in-memory queue of xAPI 2.0 statements
LernkitScorm12Adapter	Packaged SCORM 1.2 SCO	Bridges to the LMS's window.API via the runtime

All three are exported from the package root:

import {
  NoopAdapter,
  XapiStubAdapter,
  LernkitScorm12Adapter,
} from '@lernkit/tracker';

NoopAdapter

const tracker = new NoopAdapter();
await tracker.init();   // → true
await tracker.complete();
await tracker.terminate();

Use when you need a Tracker shape but no actual reporting:

• Unit tests for components that take a tracker prop.
• Static preview / live dev when you don't care about emitted events.

tracker.state reflects the calls (so UI that conditionalizes on state.completion === 'completed' works), but nothing escapes the instance.

XapiStubAdapter

const tracker = new XapiStubAdapter('rf-training/section-1/review');
await tracker.init();
await tracker.recordInteraction({ /* ... */ });
await tracker.complete();
console.log(tracker.statements);  // ← inspect the queue

Builds xAPI 2.0 statements in memory. The first constructor argument is the activity ID, used as the activity IRI in every emitted statement.

The dev course renders the statement queue in a <details> panel below each quiz; authors can eyeball the wire format without an LRS.

tracker.statements is a read-only snapshot. tracker.clearStatements() empties the queue (useful in tests).

LernkitScorm12Adapter

// In a component, only available inside a packaged SCORM SCO
if (window.LernkitScorm12?.available) {
  const tracker = new LernkitScorm12Adapter();
  await tracker.init();
  await tracker.setScore({ scaled: 0.85 });
  await tracker.complete();
  await tracker.pass();
  await tracker.terminate();
}

Bridges Tracker calls to the SCORM 1.2 window.API. The adapter doesn't import the runtime; it consumes whatever window.LernkitScorm12 exposes at call time. The runtime itself is injected into each lesson HTML by the packager.

Tracker → SCORM 1.2 wire mapping

Tracker call	SCORM 1.2 effect
setProgress(p)	Stashes { progress: p } into cmi.suspend_data (no native progress field in 1.2)
setBookmark(s)	cmi.core.lesson_location (255-char cap; truncated)
setScore(s)	cmi.core.score.raw/min/max; s.scaled × 100 per convention
complete()	cmi.core.lesson_status = 'completed'
pass()	cmi.core.lesson_status = 'passed'
fail()	cmi.core.lesson_status = 'failed'
recordInteraction(i)	Buffered in-adapter; not yet written to cmi.interactions.N (Phase 1+)

Constructor injection (for tests)

const fakeRuntime = { /* implements LernkitScorm12Runtime */ };
const tracker = new LernkitScorm12Adapter(fakeRuntime);

Skip window.LernkitScorm12 lookup; useful for unit tests.

Choosing at runtime

You usually shouldn't pick the adapter manually. The pickTracker(activityId) helper does it for you based on whether you're inside a packaged SCO.

Where to go next

• pickTracker — automatic adapter selection.
• API reference — generated from TSDoc.