react-native-webrtc/src/EventEmitter.ts

WebRTC for React Native

import { NativeModules, NativeEventEmitter, EmitterSubscription } from 'react-native';
// @ts-ignore
import EventEmitter from 'react-native/Libraries/vendor/emitter/EventEmitter';

const { WebRTCModule } = NativeModules;

// This emitter is going to be used to listen to all the native events (once) and then
// re-emit them on a JS-only emitter.
const nativeEmitter = new NativeEventEmitter(WebRTCModule);

const NATIVE_EVENTS = [
    'peerConnectionSignalingStateChanged',
    'peerConnectionStateChanged',
    'peerConnectionOnRenegotiationNeeded',
    'peerConnectionIceConnectionChanged',
    'peerConnectionIceGatheringChanged',
    'peerConnectionGotICECandidate',
    'peerConnectionDidOpenDataChannel',
    'peerConnectionOnRemoveTrack',
    'peerConnectionOnTrack',
    'dataChannelStateChanged',
    'dataChannelReceiveMessage',
    'dataChannelDidChangeBufferedAmount',
    'mediaStreamTrackMuteChanged',
    'mediaStreamTrackEnded',
];

const eventEmitter = new EventEmitter();

export function setupNativeEvents() {
    for (const eventName of NATIVE_EVENTS) {
        nativeEmitter.addListener(eventName, (...args) => {
            eventEmitter.emit(eventName, ...args);
        });
    }
}

type EventHandler = (event: unknown) => void;
type Listener = unknown;

const _subscriptions: Map<Listener, EmitterSubscription[]> = new Map();

export function addListener(listener: Listener, eventName: string, eventHandler: EventHandler): void {
    if (!NATIVE_EVENTS.includes(eventName)) {
        throw new Error(`Invalid event: ${eventName}`);
    }

    if (!_subscriptions.has(listener)) {
        _subscriptions.set(listener, []);
    }

    _subscriptions.get(listener)?.push(eventEmitter.addListener(eventName, eventHandler));
}

export function removeListener(listener: Listener): void {
    _subscriptions.get(listener)?.forEach(sub => {
        sub.remove();
    });

    _subscriptions.delete(listener);
}