Skip to content

KernstraDocs Web SDKv1.0.0

Nothing matches “”. Try an option name likeaccentColor or a method like goToPage.

Get started (opens in a new tab)Changelog (opens in a new tab)Playground (opens in a new tab)JavaScript PDF viewer (opens in a new tab)Get a free key (opens in a new tab)

PDFViewer.on()

Subscribe to a typed event. Document lifecycle events (initialized, licenseChanged, documentLoaded, documentClosed) are global and fire on Kernstra.events, not here; a handler registered on the wrong emitter never runs and never warns — see EventEmitter.

methodEventssince 1.0.0

Signature

on<K extends keyof ViewerEventMap>(event: K, handler: (data: ViewerEventMap[K]) => void, options?: SubscribeOptions): () => void

Parameters

Parameter	Type	Description
event	keyof ViewerEventMap	A per-viewer event name — see Events.
handler	(data: ViewerEventMap[K]) => void	Receives the typed payload.
options?	SubscribeOptions	`once` hears the next emit only; `signal` unsubscribes when an `AbortSignal` aborts (a signal already aborted subscribes nothing).

Returns

() => void The unsubscribe.

Throws

INVALID_STATE after destroy().

Example

TypeScript

const stop = viewer.on('pageChanged', ({ pageIndex }) => setCurrentPage(pageIndex));
stop();

const controller = new AbortController();
viewer.on('zoomChanged', ({ scale }) => setZoom(scale), { signal: controller.signal });
viewer.on('documentChanged', () => markDirty(), { signal: controller.signal });
controller.abort(); // both gone