Event API

The event namespace provides cross-window event dispatching across WebView2 instances.

event

event.emit

Broadcast an event to every window. Receivers get an event named event whose data is { payload, sourceWindowId }.

Parameter	Type	Required	Description
event	string	Yes	Event name the receivers subscribe to. Must not be empty.
payload	any	No	Data delivered as payload; absent or null sends an empty object.
excludeSelf	boolean	No	Leave out the calling window. Default: false.

Returns

Field	Type	Description
recipients	integer	How many windows the event was sent to, counted from the open windows.

success is true on success. On failure the response is { success: false, error, code }; see Error codes for code.

await fb2k.invoke('event.emit', { event: 'ui:themeChanged', payload: { theme: 'dark' } });

event.emitTo

Send an event to one window. It receives an event named event whose data is { payload, sourceWindowId }. A window id no open window has fails with NOT_FOUND.

Parameter	Type	Required	Description
event	string	Yes	Event name the receiver subscribes to. Must not be empty.
targetWindowId	string	Yes	Id of the window to send to, such as main or the windowId a port reported. Must not be empty.
payload	any	No	Data delivered as payload; absent or null sends an empty object.

Returns

success is true on success. On failure the response is { success: false, error, code }; see Error codes for code.

await fb2k.invoke('event.emitTo', { event: 'lyrics:update', targetWindowId: 'popup_01', payload: { line: 5 } });

Event envelopes

• event.emit broadcasts the requested event name, and event.emitTo targets a specific window. Receivers get the envelope { payload, sourceWindowId }; excludeSelf applies only to event.emit. Use the namespace:eventName convention for application-defined events, such as ui:themeChanged or lyrics:update.