diff --git a/.eslintrc.js b/.eslintrc.js
index a6e8e749f..0356dd2b8 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -1,5 +1,6 @@
 module.exports = {
     'extends': [
         '@jitsi/eslint-config'
-    ]
+    ],
+    'ignorePatterns': [ '*.d.ts' ]
 };
diff --git a/globals.d.ts b/globals.d.ts
new file mode 100644
index 000000000..88dacf7c4
--- /dev/null
+++ b/globals.d.ts
@@ -0,0 +1,6 @@
+export {};
+
+declare global {
+    const APP: any;
+    const interfaceConfig: any;
+}
diff --git a/react/features/base/conference/functions.js b/react/features/base/conference/functions.ts
similarity index 82%
rename from react/features/base/conference/functions.js
rename to react/features/base/conference/functions.ts
index e6ec7f6ba..7ef042ea1 100644
--- a/react/features/base/conference/functions.js
+++ b/react/features/base/conference/functions.ts
@@ -1,25 +1,24 @@
-// @flow
-
 import { sha512_256 as sha512 } from 'js-sha512';
 import _ from 'lodash';
 
+// @ts-ignore
 import { getName } from '../../app/functions';
+import { IState, IStore } from '../../app/types';
 import { determineTranscriptionLanguage } from '../../transcribing/functions';
+import { IStateful } from '../app/types';
 import { JitsiTrackErrors } from '../lib-jitsi-meet';
 import {
-    getLocalParticipant,
     hiddenParticipantJoined,
     hiddenParticipantLeft,
     participantJoined,
     participantLeft
-} from '../participants';
-import { toState } from '../redux';
-import {
-    getBackendSafePath,
-    getJitsiMeetGlobalNS,
-    safeDecodeURIComponent
-} from '../util';
+} from '../participants/actions';
+import { getLocalParticipant } from '../participants/functions';
+import { toState } from '../redux/functions';
+import { getJitsiMeetGlobalNS } from '../util/helpers';
+import { getBackendSafePath, safeDecodeURIComponent } from '../util/uri';
 
+// @ts-ignore
 import { setObfuscatedRoom } from './actions';
 import {
     AVATAR_URL_COMMAND,
@@ -27,22 +26,23 @@ import {
     JITSI_CONFERENCE_URL_KEY
 } from './constants';
 import logger from './logger';
+import { IJitsiConference } from './reducer';
 
 /**
  * Returns root conference state.
  *
- * @param {Object} state - Global state.
+ * @param {IState} state - Global state.
  * @returns {Object} Conference state.
  */
-export const getConferenceState = (state: Object) => state['features/base/conference'];
+export const getConferenceState = (state: IState) => state['features/base/conference'];
 
 /**
  * Is the conference joined or not.
  *
- * @param {Object} state - Global state.
+ * @param {IState} state - Global state.
  * @returns {boolean}
  */
-export const getIsConferenceJoined = (state: Object) => Boolean(getConferenceState(state).conference);
+export const getIsConferenceJoined = (state: IState) => Boolean(getConferenceState(state).conference);
 
 /**
  * Attach a set of local tracks to a conference.
@@ -53,7 +53,7 @@ export const getIsConferenceJoined = (state: Object) => Boolean(getConferenceSta
  * @returns {Promise}
  */
 export function _addLocalTracksToConference(
-        conference: { addTrack: Function, getLocalTracks: Function },
+        conference: IJitsiConference,
         localTracks: Array<Object>) {
     const conferenceLocalTracks = conference.getLocalTracks();
     const promises = [];
@@ -63,7 +63,7 @@ export function _addLocalTracksToConference(
         // adding one and the same video track multiple times.
         if (conferenceLocalTracks.indexOf(track) === -1) {
             promises.push(
-                conference.addTrack(track).catch(err => {
+                conference.addTrack(track).catch((err: Error) => {
                     _reportError(
                         'Failed to add local track to conference',
                         err);
@@ -86,16 +86,16 @@ export function _addLocalTracksToConference(
  * @returns {void}
  */
 export function commonUserJoinedHandling(
-        { dispatch }: Object,
-        conference: Object,
-        user: Object) {
+        { dispatch }: IStore,
+        conference: IJitsiConference,
+        user: any) {
     const id = user.getId();
     const displayName = user.getDisplayName();
 
     if (user.isHidden()) {
         dispatch(hiddenParticipantJoined(id, displayName));
     } else {
-        const isReplacing = user.isReplacing && user.isReplacing();
+        const isReplacing = user?.isReplacing();
 
         dispatch(participantJoined({
             botType: user.getBotType(),
@@ -122,15 +122,15 @@ export function commonUserJoinedHandling(
  * @returns {void}
  */
 export function commonUserLeftHandling(
-        { dispatch }: Object,
-        conference: Object,
-        user: Object) {
+        { dispatch }: IStore,
+        conference: IJitsiConference,
+        user: any) {
     const id = user.getId();
 
     if (user.isHidden()) {
         dispatch(hiddenParticipantLeft(id));
     } else {
-        const isReplaced = user.isReplaced && user.isReplaced();
+        const isReplaced = user.isReplaced?.();
 
         dispatch(participantLeft(id, conference, { isReplaced }));
     }
@@ -140,7 +140,7 @@ export function commonUserLeftHandling(
  * Evaluates a specific predicate for each {@link JitsiConference} known to the
  * redux state features/base/conference while it returns {@code true}.
  *
- * @param {Function | Object} stateful - The redux store, state, or
+ * @param {IStateful} stateful - The redux store, state, or
  * {@code getState} function.
  * @param {Function} predicate - The predicate to evaluate for each
  * {@code JitsiConference} know to the redux state features/base/conference
@@ -150,8 +150,8 @@ export function commonUserLeftHandling(
  * features/base/conference.
  */
 export function forEachConference(
-        stateful: Function | Object,
-        predicate: (Object, URL) => boolean) {
+        stateful: IStateful,
+        predicate: (a: any, b: URL) => boolean) {
     const state = getConferenceState(toState(stateful));
 
     for (const v of Object.values(state)) {
@@ -178,48 +178,48 @@ export function forEachConference(
 /**
  * Returns the display name of the conference.
  *
- * @param {Function | Object} stateful - Reference that can be resolved to Redux
+ * @param {IStateful} stateful - Reference that can be resolved to Redux
  * state with the {@code toState} function.
  * @returns {string}
  */
-export function getConferenceName(stateful: Function | Object): string {
+export function getConferenceName(stateful: IStateful): string {
     const state = toState(stateful);
     const { callee } = state['features/base/jwt'];
     const { callDisplayName } = state['features/base/config'];
     const { localSubject, room, subject } = getConferenceState(state);
 
-    return localSubject
+    return (localSubject
         || subject
         || callDisplayName
-        || (callee && callee.name)
-        || (room && safeStartCase(safeDecodeURIComponent(room)));
+        || callee?.name
+        || (room && safeStartCase(safeDecodeURIComponent(room)))) ?? '';
 }
 
 /**
  * Returns the name of the conference formatted for the title.
  *
- * @param {Function | Object} stateful - Reference that can be resolved to Redux state with the {@code toState}
+ * @param {IStateful} stateful - Reference that can be resolved to Redux state with the {@code toState}
  * function.
  * @returns {string} - The name of the conference formatted for the title.
  */
-export function getConferenceNameForTitle(stateful: Function | Object) {
-    return safeStartCase(safeDecodeURIComponent(getConferenceState(toState(stateful)).room));
+export function getConferenceNameForTitle(stateful: IStateful) {
+    return safeStartCase(safeDecodeURIComponent(getConferenceState(toState(stateful)).room ?? ''));
 }
 
 /**
  * Returns an object aggregating the conference options.
  *
- * @param {Object|Function} stateful - The redux store state.
+ * @param {IStateful} stateful - The redux store state.
  * @returns {Object} - Options object.
  */
-export function getConferenceOptions(stateful: Function | Object) {
+export function getConferenceOptions(stateful: IStateful) {
     const state = toState(stateful);
 
     const config = state['features/base/config'];
     const { locationURL } = state['features/base/connection'];
     const { tenant } = state['features/base/jwt'];
-    const { email, name: nick } = getLocalParticipant(state);
-    const options = { ...config };
+    const { email, name: nick } = getLocalParticipant(state) ?? {};
+    const options: any = { ...config };
 
     if (tenant) {
         options.siteID = tenant;
@@ -257,11 +257,11 @@ export function getConferenceOptions(stateful: Function | Object) {
 /**
 * Returns the UTC timestamp when the first participant joined the conference.
 *
-* @param {Function | Object} stateful - Reference that can be resolved to Redux
+* @param {IStateful} stateful - Reference that can be resolved to Redux
 * state with the {@code toState} function.
 * @returns {number}
 */
-export function getConferenceTimestamp(stateful: Function | Object): number {
+export function getConferenceTimestamp(stateful: IStateful) {
     const state = toState(stateful);
     const { conferenceTimestamp } = getConferenceState(state);
 
@@ -274,11 +274,11 @@ export function getConferenceTimestamp(stateful: Function | Object): number {
  * {@code conference} state of the feature base/conference which is not joining
  * but may be leaving already.
  *
- * @param {Function|Object} stateful - The redux store, state, or
+ * @param {IStateful} stateful - The redux store, state, or
  * {@code getState} function.
  * @returns {JitsiConference|undefined}
  */
-export function getCurrentConference(stateful: Function | Object) {
+export function getCurrentConference(stateful: IStateful): any {
     const { conference, joining, leaving, membersOnly, passwordRequired }
         = getConferenceState(toState(stateful));
 
@@ -293,25 +293,29 @@ export function getCurrentConference(stateful: Function | Object) {
 /**
  * Returns the stored room name.
  *
- * @param {Object} state - The current state of the app.
+ * @param {IState} state - The current state of the app.
  * @returns {string}
  */
-export function getRoomName(state: Object): string {
+export function getRoomName(state: IState) {
     return getConferenceState(state).room;
 }
 
 /**
  * Get an obfuscated room name or create and persist it if it doesn't exists.
  *
- * @param {Object} state - The current state of the app.
+ * @param {IState} state - The current state of the app.
  * @param {Function} dispatch - The Redux dispatch function.
  * @returns {string} - Obfuscated room name.
  */
-export function getOrCreateObfuscatedRoomName(state: Object, dispatch: Function) {
+export function getOrCreateObfuscatedRoomName(state: IState, dispatch: IStore['dispatch']) {
     let { obfuscatedRoom } = getConferenceState(state);
     const { obfuscatedRoomSource } = getConferenceState(state);
     const room = getRoomName(state);
 
+    if (!room) {
+        return;
+    }
+
     // On native mobile the store doesn't clear when joining a new conference so we might have the obfuscatedRoom
     // stored even though a different room was joined.
     // Check if the obfuscatedRoom was already computed for the current room.
@@ -327,11 +331,11 @@ export function getOrCreateObfuscatedRoomName(state: Object, dispatch: Function)
  * Analytics may require an obfuscated room name, this functions decides based on a config if the normal or
  * obfuscated room name should be returned.
  *
- * @param {Object} state - The current state of the app.
+ * @param {IState} state - The current state of the app.
  * @param {Function} dispatch - The Redux dispatch function.
  * @returns {string} - Analytics room name.
  */
-export function getAnalyticsRoomName(state: Object, dispatch: Function) {
+export function getAnalyticsRoomName(state: IState, dispatch: IStore['dispatch']) {
     const { analysis: { obfuscateRoomName = false } = {} } = state['features/base/config'];
 
     if (obfuscateRoomName) {
@@ -365,7 +369,7 @@ function getWiFiStatsMethod() {
  * @protected
  * @returns {void}
  */
-export function _handleParticipantError(err: { message: ?string }) {
+export function _handleParticipantError(err: Error) {
     // XXX DataChannels are initialized at some later point when the conference
     // has multiple participants, but code that pins or selects a participant
     // might be executed before. So here we're swallowing a particular error.
@@ -384,7 +388,7 @@ export function _handleParticipantError(err: { message: ?string }) {
  * @returns {boolean} If the specified room name is valid, then true; otherwise,
  * false.
  */
-export function isRoomValid(room: ?string) {
+export function isRoomValid(room?: string) {
     return typeof room === 'string' && room !== '';
 }
 
@@ -397,11 +401,11 @@ export function isRoomValid(room: ?string) {
  * @returns {Promise}
  */
 export function _removeLocalTracksFromConference(
-        conference: { removeTrack: Function },
+        conference: IJitsiConference,
         localTracks: Array<Object>) {
     return Promise.all(localTracks.map(track =>
         conference.removeTrack(track)
-            .catch(err => {
+            .catch((err: Error) => {
                 // Local track might be already disposed by direct
                 // JitsiTrack#dispose() call. So we should ignore this error
                 // here.
@@ -425,7 +429,7 @@ export function _removeLocalTracksFromConference(
  * @private
  * @returns {void}
  */
-function _reportError(msg, err) {
+function _reportError(msg: string, err: Error) {
     // TODO This is a good point to call some global error handler when we have
     // one.
     logger.error(msg, err);
@@ -443,17 +447,14 @@ function _reportError(msg, err) {
  * @returns {void}
  */
 export function sendLocalParticipant(
-        stateful: Function | Object,
-        conference: {
-            sendCommand: Function,
-            setDisplayName: Function,
-            setLocalParticipantProperty: Function }) {
+        stateful: IStateful,
+        conference: IJitsiConference) {
     const {
         avatarURL,
         email,
         features,
         name
-    } = getLocalParticipant(stateful);
+    } = getLocalParticipant(stateful) ?? {};
 
     avatarURL && conference.sendCommand(AVATAR_URL_COMMAND, {
         value: avatarURL
diff --git a/react/features/base/conference/logger.js b/react/features/base/conference/logger.ts
similarity index 91%
rename from react/features/base/conference/logger.js
rename to react/features/base/conference/logger.ts
index bc08bb126..61af7ad1a 100644
--- a/react/features/base/conference/logger.js
+++ b/react/features/base/conference/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../logging/functions';
 
 export default getLogger('features/base/conference');
diff --git a/react/features/base/conference/reducer.ts b/react/features/base/conference/reducer.ts
index 42d71308f..361c0c6b1 100644
--- a/react/features/base/conference/reducer.ts
+++ b/react/features/base/conference/reducer.ts
@@ -40,11 +40,26 @@ const DEFAULT_STATE = {
     passwordRequired: undefined
 };
 
+export interface IJitsiConference {
+    addTrack: Function;
+    getBreakoutRooms: Function;
+    getLocalTracks: Function;
+    isAVModerationSupported: Function;
+    isEndConferenceSupported: Function;
+    isLobbySupported: Function;
+    removeTrack: Function;
+    sendCommand: Function;
+    sendEndpointMessage: Function;
+    sessionId: string;
+    setDisplayName: Function;
+    setLocalParticipantProperty: Function;
+}
+
 export interface IConferenceState {
     authEnabled?: boolean;
     authLogin?: string;
     authRequired?: Object;
-    conference?: any;
+    conference?: IJitsiConference;
     conferenceTimestamp?: number;
     e2eeSupported?: boolean;
     error?: Error;
diff --git a/react/features/base/config/configType.ts b/react/features/base/config/configType.ts
index 43e1d585a..93636905d 100644
--- a/react/features/base/config/configType.ts
+++ b/react/features/base/config/configType.ts
@@ -125,6 +125,7 @@ export interface IConfig {
         key: ButtonsWithNotifyClick;
         preventExecution: boolean;
     }>;
+    callDisplayName?: string;
     callStatsConfigParams?: {
         additionalIDs?: {
             customerID?: string;
diff --git a/react/features/base/config/reducer.ts b/react/features/base/config/reducer.ts
index 13476cb81..e8ed0f742 100644
--- a/react/features/base/config/reducer.ts
+++ b/react/features/base/config/reducer.ts
@@ -71,7 +71,11 @@ const CONFERENCE_HEADER_MAPPING: any = {
 };
 
 export interface IConfigState extends IConfig {
+    analysis?: {
+        obfuscateRoomName?: boolean;
+    };
     error?: Error;
+    firefox_fake_device?: string;
 }
 
 ReducerRegistry.register<IConfigState>('features/base/config', (state = _getInitialState(), action): IConfigState => {
diff --git a/react/features/base/jwt/reducer.ts b/react/features/base/jwt/reducer.ts
index 481ebf6ea..0db8ead01 100644
--- a/react/features/base/jwt/reducer.ts
+++ b/react/features/base/jwt/reducer.ts
@@ -4,9 +4,13 @@ import { equals } from '../redux/functions';
 import { SET_JWT } from './actionTypes';
 
 export interface IJwtState {
+    callee?: {
+        name: string;
+    };
     group?: string;
     jwt?: string;
     server?: string;
+    tenant?: string;
 }
 
 /**
diff --git a/react/features/base/media/actions.js b/react/features/base/media/actions.ts
similarity index 96%
rename from react/features/base/media/actions.js
rename to react/features/base/media/actions.ts
index 76f2e75f0..76dfc38fc 100644
--- a/react/features/base/media/actions.js
+++ b/react/features/base/media/actions.ts
@@ -1,10 +1,8 @@
-/* @flow */
-
-import type { Dispatch } from 'redux';
+import { Dispatch } from 'redux';
 
 import { showModeratedNotification } from '../../av-moderation/actions';
 import { shouldShowModeratedNotification } from '../../av-moderation/functions';
-import { isModerationNotificationDisplayed } from '../../notifications';
+import { isModerationNotificationDisplayed } from '../../notifications/functions';
 
 import {
     SET_AUDIO_MUTED,
@@ -55,7 +53,7 @@ export function setAudioAvailable(available: boolean) {
  *     muted: boolean
  * }}
  */
-export function setAudioMuted(muted: boolean, ensureTrack: boolean = false) {
+export function setAudioMuted(muted: boolean, ensureTrack = false) {
     return {
         type: SET_AUDIO_MUTED,
         ensureTrack,
@@ -70,7 +68,7 @@ export function setAudioMuted(muted: boolean, ensureTrack: boolean = false) {
  * @param {boolean|undefined} skipNotification - True if we want to skip showing the notification.
  * @returns {Function}
  */
-export function setAudioUnmutePermissions(blocked: boolean, skipNotification: boolean = false) {
+export function setAudioUnmutePermissions(blocked: boolean, skipNotification = false) {
     return {
         type: SET_AUDIO_UNMUTE_PERMISSIONS,
         blocked,
@@ -107,7 +105,7 @@ export function setScreenshareMuted(
         muted: boolean,
         mediaType: MediaType = MEDIA_TYPE.SCREENSHARE,
         authority: number = SCREENSHARE_MUTISM_AUTHORITY.USER,
-        ensureTrack: boolean = false) {
+        ensureTrack = false) {
     return (dispatch: Dispatch<any>, getState: Function) => {
         const state = getState();
 
@@ -168,7 +166,7 @@ export function setVideoMuted(
         muted: boolean,
         mediaType: string = MEDIA_TYPE.VIDEO,
         authority: number = VIDEO_MUTISM_AUTHORITY.USER,
-        ensureTrack: boolean = false) {
+        ensureTrack = false) {
     return (dispatch: Dispatch<any>, getState: Function) => {
         const state = getState();
 
@@ -203,7 +201,7 @@ export function setVideoMuted(
  * @param {boolean|undefined} skipNotification - True if we want to skip showing the notification.
  * @returns {Function}
  */
-export function setVideoUnmutePermissions(blocked: boolean, skipNotification: boolean = false) {
+export function setVideoUnmutePermissions(blocked: boolean, skipNotification = false) {
     return {
         type: SET_VIDEO_UNMUTE_PERMISSIONS,
         blocked,
diff --git a/react/features/base/participants/types.ts b/react/features/base/participants/types.ts
index 6f2c140cf..bf699eac5 100644
--- a/react/features/base/participants/types.ts
+++ b/react/features/base/participants/types.ts
@@ -8,7 +8,7 @@ export interface Participant {
     e2eeSupported?: boolean;
     email?: string;
     features?: {
-        'screen-sharing'?: boolean;
+        'screen-sharing'?: boolean | string;
     };
     getId?: Function;
     id: string;
diff --git a/react/features/base/testing/actions.js b/react/features/base/testing/actions.ts
similarity index 100%
rename from react/features/base/testing/actions.js
rename to react/features/base/testing/actions.ts
diff --git a/react/features/base/testing/functions.js b/react/features/base/testing/functions.ts
similarity index 75%
rename from react/features/base/testing/functions.js
rename to react/features/base/testing/functions.ts
index 9907ddd8d..0086e2209 100644
--- a/react/features/base/testing/functions.js
+++ b/react/features/base/testing/functions.ts
@@ -1,8 +1,9 @@
-// @flow
-
-import { getMultipleVideoSupportFeatureFlag } from '../config';
-import { MEDIA_TYPE, VIDEO_TYPE } from '../media';
-import { getParticipantById } from '../participants';
+import { IState, IStore } from '../../app/types';
+import { getMultipleVideoSupportFeatureFlag } from '../config/functions.any';
+import { MEDIA_TYPE, VIDEO_TYPE } from '../media/constants';
+import { getParticipantById } from '../participants/functions';
+// eslint-disable-next-line lines-around-comment
+// @ts-ignore
 import { getTrackByMediaTypeAndParticipant, getVirtualScreenshareParticipantTrack } from '../tracks';
 
 /**
@@ -10,23 +11,23 @@ import { getTrackByMediaTypeAndParticipant, getVirtualScreenshareParticipantTrac
  * {@link TestHint} and other components from the testing package will be
  * rendered in various places across the app to help with automatic testing.
  *
- * @param {Object} state - The redux store state.
+ * @param {IState} state - The redux store state.
  * @returns {boolean}
  */
-export function isTestModeEnabled(state: Object): boolean {
+export function isTestModeEnabled(state: IState): boolean {
     const testingConfig = state['features/base/config'].testing;
 
-    return Boolean(testingConfig && testingConfig.testMode);
+    return Boolean(testingConfig?.testMode);
 }
 
 /**
  * Returns the video type of the remote participant's video.
  *
- * @param {Store} store - The redux store.
+ * @param {IStore} store - The redux store.
  * @param {string} id - The participant ID for the remote video.
  * @returns {VIDEO_TYPE}
  */
-export function getRemoteVideoType({ getState }: Object, id: String): VIDEO_TYPE {
+export function getRemoteVideoType({ getState }: IStore, id: string) {
     const state = getState();
     const participant = getParticipantById(state, id);
 
@@ -40,13 +41,13 @@ export function getRemoteVideoType({ getState }: Object, id: String): VIDEO_TYPE
 /**
  * Returns whether the last media event received for large video indicates that the video is playing, if not muted.
  *
- * @param {Store} store - The redux store.
+ * @param {IStore} store - The redux store.
  * @returns {boolean}
  */
-export function isLargeVideoReceived({ getState }: Object): boolean {
+export function isLargeVideoReceived({ getState }: IStore): boolean {
     const state = getState();
     const largeVideoParticipantId = state['features/large-video'].participantId;
-    const largeVideoParticipant = getParticipantById(state, largeVideoParticipantId);
+    const largeVideoParticipant = getParticipantById(state, largeVideoParticipantId ?? '');
     const tracks = state['features/base/tracks'];
     let videoTrack;
 
@@ -64,11 +65,11 @@ export function isLargeVideoReceived({ getState }: Object): boolean {
 /**
  * Returns whether the last media event received for a remote video indicates that the video is playing, if not muted.
  *
- * @param {Store} store - The redux store.
+ * @param {IStore} store - The redux store.
  * @param {string} id - The participant ID for the remote video.
  * @returns {boolean}
  */
-export function isRemoteVideoReceived({ getState }: Object, id: String): boolean {
+export function isRemoteVideoReceived({ getState }: IStore, id: string): boolean {
     const state = getState();
     const tracks = state['features/base/tracks'];
     const participant = getParticipantById(state, id);
diff --git a/react/features/face-landmarks/functions.ts b/react/features/face-landmarks/functions.ts
index af134d942..456ce60b3 100644
--- a/react/features/face-landmarks/functions.ts
+++ b/react/features/face-landmarks/functions.ts
@@ -111,7 +111,7 @@ export async function sendFaceExpressionsWebhook(state: IState) {
 
     const reqBody = {
         meetingFqn: extractFqnFromPath(),
-        sessionId: conference.sessionId,
+        sessionId: conference?.sessionId,
         submitted: Date.now(),
         emotions: faceExpressionsBuffer,
         participantId: localParticipant?.jwtId,
diff --git a/react/features/notifications/functions.js b/react/features/notifications/functions.ts
similarity index 71%
rename from react/features/notifications/functions.js
rename to react/features/notifications/functions.ts
index 11cf3ed7c..586012205 100644
--- a/react/features/notifications/functions.js
+++ b/react/features/notifications/functions.ts
@@ -1,19 +1,16 @@
-// @flow
-
 import { MODERATION_NOTIFICATIONS } from '../av-moderation/constants';
-import { MEDIA_TYPE } from '../base/media';
-import { toState } from '../base/redux';
-
-declare var interfaceConfig: Object;
+import { IStateful } from '../base/app/types';
+import { MediaType } from '../base/media/constants';
+import { toState } from '../base/redux/functions';
 
 /**
  * Tells whether or not the notifications are enabled and if there are any
  * notifications to be displayed based on the current Redux state.
  *
- * @param {Object|Function} stateful - The redux store state.
+ * @param {IStateful} stateful - The redux store state.
  * @returns {boolean}
  */
-export function areThereNotifications(stateful: Object | Function) {
+export function areThereNotifications(stateful: IStateful) {
     const state = toState(stateful);
     const { enabled, notifications } = state['features/notifications'];
 
@@ -33,10 +30,10 @@ export function joinLeaveNotificationsDisabled() {
  * Returns whether or not the moderation notification for the given type is displayed.
  *
  * @param {MEDIA_TYPE} mediaType - The media type to check.
- * @param {Object | Function} stateful - The redux store state.
+ * @param {IStateful} stateful - The redux store state.
  * @returns {boolean}
  */
-export function isModerationNotificationDisplayed(mediaType: MEDIA_TYPE, stateful: Object | Function) {
+export function isModerationNotificationDisplayed(mediaType: MediaType, stateful: IStateful) {
     const state = toState(stateful);
 
     const { notifications } = state['features/notifications'];
diff --git a/react/features/prejoin/components/Prejoin.native.tsx b/react/features/prejoin/components/Prejoin.native.tsx
index 900a5330f..2fc7b2dee 100644
--- a/react/features/prejoin/components/Prejoin.native.tsx
+++ b/react/features/prejoin/components/Prejoin.native.tsx
@@ -65,7 +65,7 @@ const Prejoin: React.FC<PrejoinProps> = ({ navigation }: PrejoinProps) => {
     );
     const localParticipant = useSelector((state: IState) => getLocalParticipant(state));
     const isDisplayNameMandatory = useSelector(state => isDisplayNameRequired(state));
-    const roomName = useSelector(state => getConferenceName(state));
+    const roomName = useSelector((state: IState) => getConferenceName(state));
     const participantName = localParticipant?.name;
     const [ displayName, setDisplayName ]
         = useState(participantName || '');
diff --git a/react/features/reactions/functions.any.ts b/react/features/reactions/functions.any.ts
index a88cd3c9b..ab6d1a9a3 100644
--- a/react/features/reactions/functions.any.ts
+++ b/react/features/reactions/functions.any.ts
@@ -69,7 +69,7 @@ export async function sendReactionsWebhook(state: IState, reactions: Array<strin
 
     const reqBody = {
         meetingFqn: extractFqnFromPath(),
-        sessionId: conference.sessionId,
+        sessionId: conference?.sessionId,
         submitted: Date.now(),
         reactions,
         participantId: localParticipant?.jwtId,
diff --git a/react/features/transcribing/functions.js b/react/features/transcribing/functions.ts
similarity index 80%
rename from react/features/transcribing/functions.js
rename to react/features/transcribing/functions.ts
index cec4be88c..2642626ce 100644
--- a/react/features/transcribing/functions.js
+++ b/react/features/transcribing/functions.ts
@@ -1,7 +1,7 @@
-// @flow
-
 import i18next from 'i18next';
 
+import { IConfig } from '../base/config/configType';
+
 import JITSI_TO_BCP47_MAP from './jitsi-bcp47-map.json';
 import logger from './logger';
 import TRANSCRIBER_LANGS from './transcriber-langs.json';
@@ -14,7 +14,7 @@ const DEFAULT_TRANSCRIBER_LANG = 'en-US';
  * @param {*} config - Application config.
  * @returns {string}
  */
-export function determineTranscriptionLanguage(config: Object) {
+export function determineTranscriptionLanguage(config: IConfig) {
     const { transcription } = config;
 
     // if transcriptions are not enabled nothing to determine
@@ -27,11 +27,11 @@ export function determineTranscriptionLanguage(config: Object) {
     // Jitsi language detections uses custom language tags, but the transcriber expects BCP-47 compliant tags,
     // we use a mapping file to convert them.
     const bcp47Locale = transcription?.useAppLanguage ?? true
-        ? JITSI_TO_BCP47_MAP[i18next.language]
+        ? JITSI_TO_BCP47_MAP[i18next.language as keyof typeof JITSI_TO_BCP47_MAP]
         : transcription?.preferredLanguage;
 
     // Check if the obtained language is supported by the transcriber
-    let safeBCP47Locale = TRANSCRIBER_LANGS[bcp47Locale] && bcp47Locale;
+    let safeBCP47Locale = TRANSCRIBER_LANGS[bcp47Locale as keyof typeof TRANSCRIBER_LANGS] && bcp47Locale;
 
     if (!safeBCP47Locale) {
         safeBCP47Locale = DEFAULT_TRANSCRIBER_LANG;
diff --git a/react/features/transcribing/logger.js b/react/features/transcribing/logger.ts
similarity index 91%
rename from react/features/transcribing/logger.js
rename to react/features/transcribing/logger.ts
index 2a56afa18..b85a6c900 100644
--- a/react/features/transcribing/logger.js
+++ b/react/features/transcribing/logger.ts
@@ -1,5 +1,3 @@
-// @flow
-
 import { getLogger } from '../base/logging/functions';
 
 export default getLogger('features/transcribing');
diff --git a/tsconfig.json b/tsconfig.json
index ba0f1e1f7..0a7a1e78b 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,5 +1,5 @@
 {
-    "include": ["react/features/**/*.ts", "react/features/**/*.tsx", "./custom.d.ts"],
+    "include": ["react/features/**/*.ts", "react/features/**/*.tsx", "./custom.d.ts", "./globals.d.ts"],
     "compilerOptions": {
         "allowSyntheticDefaultImports": true,
         "module": "es6",