grafana-statusmap/src/libs/polygrafill/funcs.ts

import { Emitter } from 'app/core/utils/emitter';

// Old Grafana releases use strings as event ids and
// new event ids in form of object {name: "event-id"} are not
// supported properly: first defined listener will receive
// all emitted events despite of the value in 'name' field.
//
// This method detects this behaviour and return true
// only for new Grafana versions.
export function hasAppEventCompatibleEmitter(emitter: Emitter):boolean {
    let receiveEvents = 0;
    let eventId: any = {name: "non-existed-event-id"};
    let eventId2: any = {name: "non-existed-event-id-2"};
    emitter.on(eventId, function(){
        receiveEvents++;
    });
    emitter.emit(eventId);
    emitter.emit(eventId2);
    emitter.removeAllListeners(eventId);

    // New Grafana versions should receive one event.
    return receiveEvents == 1;
}