lazyObserve()

Starts side effects only while one or more MobX observables are being observed.

When the first property becomes observed, onStart is called. When all tracked properties become unobserved, onEnd is called with the value returned by onStart. Cleanup can be delayed via endDelay.

It uses MobX onBecomeObserved and onBecomeUnobserved hooks to perform lazy subscription management.

Examples:

const stop = lazyObserve({
  context: store,
  property: 'items',
  onStart: () => api.subscribe(),
  onEnd: (subscription) => subscription.unsubscribe(),
});

lazyObserve({
  property: [boxA, boxB],
  onStart: () => console.log('observed'),
  endDelay: 300,
});