From 101095539323c4809f19c277b8a562ee91ae2033 Mon Sep 17 00:00:00 2001
From: Robert Pintilii <robert.pin9@gmail.com>
Date: Fri, 26 Aug 2022 12:54:16 +0300
Subject: [PATCH] ref: Convert some reducers to TS (#12065)

---
 react/features/app/types.ts                   | 27 +++++++++++++
 react/features/base/redux/functions.ts        |  2 +-
 .../audio-mode/{reducer.js => reducer.ts}     | 12 ++++--
 .../background/{reducer.js => reducer.ts}     | 11 ++++--
 .../external-api/{reducer.js => reducer.ts}   | 10 +++--
 .../full-screen/{reducer.js => reducer.ts}    | 10 +++--
 .../mobile/watchos/{reducer.js => reducer.ts} | 13 +++++--
 .../{reducer.js => reducer.ts}                | 11 ++++--
 .../{reducer.js => reducer.ts}                | 11 ++++--
 .../{constants.js => constants.ts}            |  2 -
 .../notifications/{reducer.js => reducer.ts}  | 28 ++++++++++----
 .../overlay/{reducer.js => reducer.ts}        | 31 +++++++++------
 .../{constants.js => constants.tsx}           | 10 ++---
 .../{reducer.js => reducer.ts}                | 11 +++++-
 .../features/polls/{reducer.js => reducer.ts} | 17 ++++++---
 react/features/polls/types.ts                 |  1 -
 .../power-monitor/{reducer.js => reducer.ts}  | 17 ++++++---
 .../prejoin/{reducer.js => reducer.ts}        | 38 ++++++++++++++-----
 react/features/reactions/reducer.ts           |  2 +-
 19 files changed, 183 insertions(+), 81 deletions(-)
 rename react/features/mobile/audio-mode/{reducer.js => reducer.ts} (61%)
 rename react/features/mobile/background/{reducer.js => reducer.ts} (66%)
 rename react/features/mobile/external-api/{reducer.js => reducer.ts} (55%)
 rename react/features/mobile/full-screen/{reducer.js => reducer.ts} (51%)
 rename react/features/mobile/watchos/{reducer.js => reducer.ts} (67%)
 rename react/features/no-audio-signal/{reducer.js => reducer.ts} (51%)
 rename react/features/noise-detection/{reducer.js => reducer.ts} (51%)
 rename react/features/notifications/{constants.js => constants.ts} (99%)
 rename react/features/notifications/{reducer.js => reducer.ts} (84%)
 rename react/features/overlay/{reducer.js => reducer.ts} (75%)
 rename react/features/participants-pane/{constants.js => constants.tsx} (95%)
 rename react/features/participants-pane/{reducer.js => reducer.ts} (77%)
 rename react/features/polls/{reducer.js => reducer.ts} (90%)
 rename react/features/power-monitor/{reducer.js => reducer.ts} (71%)
 rename react/features/prejoin/{reducer.js => reducer.ts} (81%)

diff --git a/react/features/app/types.ts b/react/features/app/types.ts
index 8ff940e5d..93cff24d4 100644
--- a/react/features/app/types.ts
+++ b/react/features/app/types.ts
@@ -40,7 +40,20 @@ import { IInviteState } from '../invite/reducer';
 import { IJaaSState } from '../jaas/reducer';
 import { ILargeVideoState } from '../large-video/reducer';
 import { ILobbyState } from '../lobby/reducer';
+import { IMobileAudioModeState } from '../mobile/audio-mode/reducer';
+import { IBackgroundState } from '../mobile/background/reducer';
+import { IMobileExternalApiState } from '../mobile/external-api/reducer';
+import { IFullScreenState } from '../mobile/full-screen/reducer';
+import { IMobileWatchOSState } from '../mobile/watchos/reducer';
+import { INoAudioSignalState } from '../no-audio-signal/reducer';
+import { INoiseDetectionState } from '../noise-detection/reducer';
 import { INoiseSuppressionState } from '../noise-suppression/reducer';
+import { INotificationsState } from '../notifications/reducer';
+import { IOverlayState } from '../overlay/reducer';
+import { IPollsState } from '../polls/reducer';
+import { IPowerMonitorState } from '../power-monitor/reducer';
+import { IPrejoinState } from '../prejoin/reducer';
+import { IReactionsState } from '../reactions/reducer';
 
 export interface IStore {
     dispatch: Function,
@@ -51,6 +64,7 @@ export interface IState {
     'features/analytics': IAnalyticsState,
     'features/authentication': IAuthenticationState,
     'features/av-moderation': IAVModerationState,
+    'features/background': IBackgroundState,
     'features/base/app': IAppState,
     'features/base/audio-only': IAudioOnlyState,
     'features/base/conference': IConferenceState,
@@ -85,12 +99,25 @@ export interface IState {
     'features/feedback': IFeedbackState,
     'features/filmstrip': IFilmstripState,
     'features/follow-me': IFollowMeState,
+    'features/full-screen': IFullScreenState,
     'features/gifs': IGifsState,
     'features/google-api': IGoogleApiState,
     'features/invite': IInviteState,
     'features/jaas': IJaaSState,
     'features/large-video': ILargeVideoState,
     'features/lobby': ILobbyState,
+    'features/mobile/audio-mode': IMobileAudioModeState,
+    'features/mobile/external-api': IMobileExternalApiState,
+    'features/mobile/watchos': IMobileWatchOSState,
+    'features/no-audio-signal': INoAudioSignalState,
+    'features/noise-detection': INoiseDetectionState,
     'features/noise-suppression': INoiseSuppressionState,
+    'features/notifications': INotificationsState,
+    'features/overlay': IOverlayState,
+    'features/participants-pane': IParticipantsState,
+    'features/polls': IPollsState,
+    'features/power-monitor': IPowerMonitorState,
+    'features/prejoin': IPrejoinState,
+    'features/reactions': IReactionsState,
     'features/testing': ITestingState
 }
diff --git a/react/features/base/redux/functions.ts b/react/features/base/redux/functions.ts
index 8b8ad1b71..63dcc0439 100644
--- a/react/features/base/redux/functions.ts
+++ b/react/features/base/redux/functions.ts
@@ -16,7 +16,7 @@ import { IState, IStore } from '../../app/types';
  * from the specified target by setting the specified properties to the
  * specified values.
  */
-export function assign<T extends Object>(target: T, source: T): T {
+export function assign<T extends Object>(target: T, source: Partial<T>): T {
     let t = target;
 
     for (const property in source) { // eslint-disable-line guard-for-in
diff --git a/react/features/mobile/audio-mode/reducer.js b/react/features/mobile/audio-mode/reducer.ts
similarity index 61%
rename from react/features/mobile/audio-mode/reducer.js
rename to react/features/mobile/audio-mode/reducer.ts
index e2d3e3ef8..a8245f18d 100644
--- a/react/features/mobile/audio-mode/reducer.js
+++ b/react/features/mobile/audio-mode/reducer.ts
@@ -1,15 +1,19 @@
-// @flow
-
-import { equals, set, ReducerRegistry } from '../../base/redux';
+import ReducerRegistry from '../../base/redux/ReducerRegistry';
+import { equals, set } from '../../base/redux/functions';
 
 import { _SET_AUDIOMODE_DEVICES, _SET_AUDIOMODE_SUBSCRIPTIONS } from './actionTypes';
 
+export interface IMobileAudioModeState {
+    devices: Object[];
+    subscriptions: Object[];
+}
+
 const DEFAULT_STATE = {
     devices: [],
     subscriptions: []
 };
 
-ReducerRegistry.register('features/mobile/audio-mode', (state = DEFAULT_STATE, action) => {
+ReducerRegistry.register('features/mobile/audio-mode', (state: IMobileAudioModeState = DEFAULT_STATE, action) => {
     switch (action.type) {
     case _SET_AUDIOMODE_DEVICES: {
         const { devices } = action;
diff --git a/react/features/mobile/background/reducer.js b/react/features/mobile/background/reducer.ts
similarity index 66%
rename from react/features/mobile/background/reducer.js
rename to react/features/mobile/background/reducer.ts
index e9eeea134..380cb927d 100644
--- a/react/features/mobile/background/reducer.js
+++ b/react/features/mobile/background/reducer.ts
@@ -1,12 +1,15 @@
-// @flow
-
-import { ReducerRegistry } from '../../base/redux';
+import ReducerRegistry from '../../base/redux/ReducerRegistry';
 
 import {
     _SET_APP_STATE_LISTENER,
     APP_STATE_CHANGED
 } from './actionTypes';
 
+export interface IBackgroundState {
+    appState: string;
+    appStateListener?: Function;
+}
+
 /**
  * The default/initial redux state of the feature background.
  */
@@ -14,7 +17,7 @@ const DEFAULT_STATE = {
     appState: 'active'
 };
 
-ReducerRegistry.register('features/background', (state = DEFAULT_STATE, action) => {
+ReducerRegistry.register('features/background', (state: IBackgroundState = DEFAULT_STATE, action) => {
     switch (action.type) {
     case _SET_APP_STATE_LISTENER:
         return {
diff --git a/react/features/mobile/external-api/reducer.js b/react/features/mobile/external-api/reducer.ts
similarity index 55%
rename from react/features/mobile/external-api/reducer.js
rename to react/features/mobile/external-api/reducer.ts
index f966dbd08..374eb69a8 100644
--- a/react/features/mobile/external-api/reducer.js
+++ b/react/features/mobile/external-api/reducer.ts
@@ -1,14 +1,16 @@
-// @flow
-
-import { ReducerRegistry } from '../../base/redux';
+import ReducerRegistry from '../../base/redux/ReducerRegistry';
 
 import { SCREEN_SHARE_PARTICIPANTS_UPDATED } from './actionTypes';
 
+export interface IMobileExternalApiState {
+    screenShares: string[];
+}
+
 const DEFAULT_STATE = {
     screenShares: []
 };
 
-ReducerRegistry.register('features/mobile/external-api', (state = DEFAULT_STATE, action) => {
+ReducerRegistry.register('features/mobile/external-api', (state: IMobileExternalApiState = DEFAULT_STATE, action) => {
     switch (action.type) {
     case SCREEN_SHARE_PARTICIPANTS_UPDATED: {
         return {
diff --git a/react/features/mobile/full-screen/reducer.js b/react/features/mobile/full-screen/reducer.ts
similarity index 51%
rename from react/features/mobile/full-screen/reducer.js
rename to react/features/mobile/full-screen/reducer.ts
index 2091da7df..8ea949264 100644
--- a/react/features/mobile/full-screen/reducer.js
+++ b/react/features/mobile/full-screen/reducer.ts
@@ -1,10 +1,12 @@
-// @flow
-
-import { ReducerRegistry } from '../../base/redux';
+import ReducerRegistry from '../../base/redux/ReducerRegistry';
 
 import { _SET_IMMERSIVE_LISTENER } from './actionTypes';
 
-ReducerRegistry.register('features/full-screen', (state = {}, action) => {
+export interface IFullScreenState {
+    listener?: Function;
+}
+
+ReducerRegistry.register('features/full-screen', (state: IFullScreenState = {}, action) => {
     switch (action.type) {
     case _SET_IMMERSIVE_LISTENER:
         return {
diff --git a/react/features/mobile/watchos/reducer.js b/react/features/mobile/watchos/reducer.ts
similarity index 67%
rename from react/features/mobile/watchos/reducer.js
rename to react/features/mobile/watchos/reducer.ts
index 1251b727d..020e318a2 100644
--- a/react/features/mobile/watchos/reducer.js
+++ b/react/features/mobile/watchos/reducer.ts
@@ -1,9 +1,14 @@
-// @flow
-
-import { assign, ReducerRegistry } from '../../base/redux';
+import ReducerRegistry from '../../base/redux/ReducerRegistry';
+import { assign } from '../../base/redux/functions';
 
 import { SET_CONFERENCE_TIMESTAMP, SET_SESSION_ID, SET_WATCH_REACHABLE } from './actionTypes';
 
+export interface IMobileWatchOSState {
+    conferenceTimestamp?: number;
+    sessionID: number;
+    watchReachable?: boolean;
+}
+
 const INITIAL_STATE = {
     sessionID: new Date().getTime()
 };
@@ -11,7 +16,7 @@ const INITIAL_STATE = {
 /**
  * Reduces the Redux actions of the feature features/mobile/watchos.
  */
-ReducerRegistry.register('features/mobile/watchos', (state = INITIAL_STATE, action) => {
+ReducerRegistry.register('features/mobile/watchos', (state: IMobileWatchOSState = INITIAL_STATE, action) => {
     switch (action.type) {
     case SET_CONFERENCE_TIMESTAMP: {
         return assign(state, {
diff --git a/react/features/no-audio-signal/reducer.js b/react/features/no-audio-signal/reducer.ts
similarity index 51%
rename from react/features/no-audio-signal/reducer.js
rename to react/features/no-audio-signal/reducer.ts
index 11706057e..2d06b0081 100644
--- a/react/features/no-audio-signal/reducer.js
+++ b/react/features/no-audio-signal/reducer.ts
@@ -1,13 +1,16 @@
-// @flow
-
-import { ReducerRegistry, set } from '../base/redux';
+import ReducerRegistry from '../base/redux/ReducerRegistry';
+import { set } from '../base/redux/functions';
 
 import { SET_NO_AUDIO_SIGNAL_NOTIFICATION_UID } from './actionTypes';
 
+export interface INoAudioSignalState {
+    noAudioSignalNotificationUid?: number;
+}
+
 /**
  * Reduces the redux actions of the feature no audio signal.
  */
-ReducerRegistry.register('features/no-audio-signal', (state = {}, action) => {
+ReducerRegistry.register('features/no-audio-signal', (state: INoAudioSignalState = {}, action) => {
     switch (action.type) {
     case SET_NO_AUDIO_SIGNAL_NOTIFICATION_UID:
         return set(state, 'noAudioSignalNotificationUid', action.uid);
diff --git a/react/features/noise-detection/reducer.js b/react/features/noise-detection/reducer.ts
similarity index 51%
rename from react/features/noise-detection/reducer.js
rename to react/features/noise-detection/reducer.ts
index d7a2b7a97..ff1512d13 100644
--- a/react/features/noise-detection/reducer.js
+++ b/react/features/noise-detection/reducer.ts
@@ -1,13 +1,16 @@
-// @flow
-
-import { ReducerRegistry, set } from '../base/redux';
+import ReducerRegistry from '../base/redux/ReducerRegistry';
+import { set } from '../base/redux/functions';
 
 import { SET_NOISY_AUDIO_INPUT_NOTIFICATION_UID } from './actionTypes';
 
+export interface INoiseDetectionState {
+    noisyAudioInputNotificationUid?: number;
+}
+
 /**
  * Reduces the redux actions of noise detection feature.
  */
-ReducerRegistry.register('features/noise-detection', (state = {}, action) => {
+ReducerRegistry.register('features/noise-detection', (state: INoiseDetectionState = {}, action) => {
     switch (action.type) {
     case SET_NOISY_AUDIO_INPUT_NOTIFICATION_UID:
         return set(state, 'noisyAudioInputNotificationUid', action.uid);
diff --git a/react/features/notifications/constants.js b/react/features/notifications/constants.ts
similarity index 99%
rename from react/features/notifications/constants.js
rename to react/features/notifications/constants.ts
index d480aa39a..6780875fa 100644
--- a/react/features/notifications/constants.js
+++ b/react/features/notifications/constants.ts
@@ -1,5 +1,3 @@
-// @flow
-
 /**
  * The standard time when auto-disappearing notifications should disappear.
  */
diff --git a/react/features/notifications/reducer.js b/react/features/notifications/reducer.ts
similarity index 84%
rename from react/features/notifications/reducer.js
rename to react/features/notifications/reducer.ts
index 62380ee37..7fb67c4f8 100644
--- a/react/features/notifications/reducer.js
+++ b/react/features/notifications/reducer.ts
@@ -1,6 +1,4 @@
-// @flow
-
-import { ReducerRegistry } from '../base/redux';
+import ReducerRegistry from '../base/redux/ReducerRegistry';
 
 import {
     CLEAR_NOTIFICATIONS,
@@ -20,6 +18,22 @@ const DEFAULT_STATE = {
     notifications: []
 };
 
+interface INotification {
+    component: Object;
+    props: {
+        appearance?: string;
+        descriptionKey?: string;
+        titleKey: string;
+    };
+    timeout: number;
+    uid: string;
+}
+
+export interface INotificationsState {
+    enabled: boolean;
+    notifications: INotification[];
+}
+
 /**
  * Reduces redux actions which affect the display of notifications.
  *
@@ -29,7 +43,7 @@ const DEFAULT_STATE = {
  * specified {@code action}.
  */
 ReducerRegistry.register('features/notifications',
-    (state = DEFAULT_STATE, action) => {
+    (state: INotificationsState = DEFAULT_STATE, action) => {
         switch (action.type) {
         case CLEAR_NOTIFICATIONS:
             return {
@@ -75,9 +89,9 @@ ReducerRegistry.register('features/notifications',
  * @returns {Object[]} A new array with an updated order of the notification
  * queue.
  */
-function _insertNotificationByPriority(notifications, notification) {
+function _insertNotificationByPriority(notifications: INotification[], notification: INotification) {
     const newNotificationPriority
-        = NOTIFICATION_TYPE_PRIORITIES[notification.props.appearance] || 0;
+        = NOTIFICATION_TYPE_PRIORITIES[notification.props.appearance ?? ''] || 0;
 
     // Default to putting the new notification at the end of the queue.
     let insertAtLocation = notifications.length;
@@ -88,7 +102,7 @@ function _insertNotificationByPriority(notifications, notification) {
     for (let i = 1; i < notifications.length; i++) {
         const queuedNotification = notifications[i];
         const queuedNotificationPriority
-            = NOTIFICATION_TYPE_PRIORITIES[queuedNotification.props.appearance]
+            = NOTIFICATION_TYPE_PRIORITIES[queuedNotification.props.appearance ?? '']
                 || 0;
 
         if (queuedNotificationPriority < newNotificationPriority) {
diff --git a/react/features/overlay/reducer.js b/react/features/overlay/reducer.ts
similarity index 75%
rename from react/features/overlay/reducer.js
rename to react/features/overlay/reducer.ts
index 61d400508..3bad8ff97 100644
--- a/react/features/overlay/reducer.js
+++ b/react/features/overlay/reducer.ts
@@ -1,7 +1,6 @@
-// @flow
-
-import { CONFIG_WILL_LOAD, LOAD_CONFIG_ERROR, SET_CONFIG } from '../base/config';
-import { assign, ReducerRegistry, set } from '../base/redux';
+import { CONFIG_WILL_LOAD, LOAD_CONFIG_ERROR, SET_CONFIG } from '../base/config/actionTypes';
+import ReducerRegistry from '../base/redux/ReducerRegistry';
+import { assign, set } from '../base/redux/functions';
 
 import {
     MEDIA_PERMISSION_PROMPT_VISIBILITY_CHANGED,
@@ -9,19 +8,27 @@ import {
     TOGGLE_SLOW_GUM_OVERLAY
 } from './actionTypes';
 
+export interface IOverlayState {
+    browser?: string;
+    fatalError?: Error;
+    isMediaPermissionPromptVisible?: boolean;
+    isSlowGUMOverlayVisible?: boolean;
+    loadConfigOverlayVisible?: boolean;
+}
+
 /**
  * Reduces the redux actions of the feature overlay.
  *
  * FIXME: these pieces of state should probably be in a different place.
  */
-ReducerRegistry.register('features/overlay', (state = { }, action) => {
+ReducerRegistry.register('features/overlay', (state: IOverlayState = { }, action) => {
     switch (action.type) {
     case CONFIG_WILL_LOAD:
         return _setShowLoadConfigOverlay(state, Boolean(action.room));
 
     case LOAD_CONFIG_ERROR:
     case SET_CONFIG:
-        return _setShowLoadConfigOverlay(false);
+        return _setShowLoadConfigOverlay(state, false);
 
     case MEDIA_PERMISSION_PROMPT_VISIBILITY_CHANGED:
         return _mediaPermissionPromptVisibilityChanged(state, action);
@@ -47,8 +54,8 @@ ReducerRegistry.register('features/overlay', (state = { }, action) => {
  * the specified action.
  */
 function _mediaPermissionPromptVisibilityChanged(
-        state,
-        { browser, isVisible }) {
+        state: IOverlayState,
+        { browser, isVisible }: {browser?: string, isVisible?: boolean}) {
     return assign(state, {
         browser,
         isMediaPermissionPromptVisible: isVisible
@@ -66,8 +73,8 @@ function _mediaPermissionPromptVisibilityChanged(
  * the specified action.
  */
 function _toggleSlowGUMOverlay(
-        state,
-        { isVisible }) {
+        state: IOverlayState,
+        { isVisible }: {isVisible?: boolean}) {
     return assign(state, {
         isSlowGUMOverlayVisible: isVisible
     });
@@ -81,7 +88,7 @@ function _toggleSlowGUMOverlay(
  * @returns {Object} The new state of the feature overlay after the reduction of
  * the specified action.
  */
-function _setShowLoadConfigOverlay(state, show) {
+function _setShowLoadConfigOverlay(state: IOverlayState, show?: boolean) {
     return set(state, 'loadConfigOverlayVisible', show);
 }
 
@@ -95,6 +102,6 @@ function _setShowLoadConfigOverlay(state, show) {
  * @returns {Object}
  * @private
  */
-function _setFatalError(state, { fatalError }) {
+function _setFatalError(state: IOverlayState, { fatalError }: {fatalError?: Error}) {
     return set(state, 'fatalError', fatalError);
 }
diff --git a/react/features/participants-pane/constants.js b/react/features/participants-pane/constants.tsx
similarity index 95%
rename from react/features/participants-pane/constants.js
rename to react/features/participants-pane/constants.tsx
index 62f2f8c50..abc8b0e6e 100644
--- a/react/features/participants-pane/constants.js
+++ b/react/features/participants-pane/constants.tsx
@@ -1,14 +1,12 @@
-// @flow
-
 import React from 'react';
 
+import Icon from '../base/icons/components/Icon';
 import {
-    Icon,
     IconCameraEmpty,
     IconCameraEmptyDisabled,
     IconMicrophoneEmpty,
     IconMicrophoneEmptySlash
-} from '../base/icons';
+} from '../base/icons/svg';
 
 /**
  * Reducer key for the feature.
@@ -44,8 +42,8 @@ export type QuickActionButtonType = 'Mute' | 'AskToUnmute' | 'None';
  * Enum of possible participant mute button states.
  */
 export const QUICK_ACTION_BUTTON: {
-    MUTE: QuickActionButtonType,
     ASK_TO_UNMUTE: QuickActionButtonType,
+    MUTE: QuickActionButtonType,
     NONE: QuickActionButtonType
 } = {
     MUTE: 'Mute',
@@ -56,7 +54,7 @@ export const QUICK_ACTION_BUTTON: {
 /**
  * Icon mapping for possible participant audio states.
  */
-export const AudioStateIcons: {[MediaState]: React$Element<any> | null} = {
+export const AudioStateIcons = {
     [MEDIA_STATE.DOMINANT_SPEAKER]: (
         <Icon
             className = 'jitsi-icon-dominant-speaker'
diff --git a/react/features/participants-pane/reducer.js b/react/features/participants-pane/reducer.ts
similarity index 77%
rename from react/features/participants-pane/reducer.js
rename to react/features/participants-pane/reducer.ts
index ce788cd02..d0fecda03 100644
--- a/react/features/participants-pane/reducer.js
+++ b/react/features/participants-pane/reducer.ts
@@ -1,4 +1,4 @@
-import { ReducerRegistry } from '../base/redux';
+import ReducerRegistry from '../base/redux/ReducerRegistry';
 
 import {
     PARTICIPANTS_PANE_CLOSE,
@@ -7,6 +7,13 @@ import {
 } from './actionTypes';
 import { REDUCER_KEY } from './constants';
 
+export interface IParticipantsPane {
+    isOpen: boolean;
+    participantsVolume: {
+        [participantId: string]: number;
+    }
+}
+
 const DEFAULT_STATE = {
     isOpen: false,
     participantsVolume: {}
@@ -16,7 +23,7 @@ const DEFAULT_STATE = {
  * Listen for actions that mutate the participants pane state.
  */
 ReducerRegistry.register(
-    REDUCER_KEY, (state = DEFAULT_STATE, action) => {
+    REDUCER_KEY, (state: IParticipantsPane = DEFAULT_STATE, action) => {
         switch (action.type) {
         case PARTICIPANTS_PANE_CLOSE:
             return {
diff --git a/react/features/polls/reducer.js b/react/features/polls/reducer.ts
similarity index 90%
rename from react/features/polls/reducer.js
rename to react/features/polls/reducer.ts
index afa6fa02a..1ae76fde2 100644
--- a/react/features/polls/reducer.js
+++ b/react/features/polls/reducer.ts
@@ -1,6 +1,4 @@
-// @flow
-
-import { ReducerRegistry } from '../base/redux';
+import ReducerRegistry from '../base/redux/ReducerRegistry';
 
 import {
     CHANGE_VOTE,
@@ -11,7 +9,7 @@ import {
     RETRACT_VOTE,
     RESET_NB_UNREAD_POLLS
 } from './actionTypes';
-import type { Answer } from './types';
+import { Answer, Poll } from './types';
 
 const INITIAL_STATE = {
     polls: {},
@@ -20,7 +18,14 @@ const INITIAL_STATE = {
     nbUnreadPolls: 0
 };
 
-ReducerRegistry.register('features/polls', (state = INITIAL_STATE, action) => {
+export interface IPollsState {
+    nbUnreadPolls: number;
+    polls: {
+        [pollId: string]: Poll
+    };
+}
+
+ReducerRegistry.register('features/polls', (state: IPollsState = INITIAL_STATE, action) => {
     switch (action.type) {
 
     case CHANGE_VOTE: {
@@ -66,7 +71,7 @@ ReducerRegistry.register('features/polls', (state = INITIAL_STATE, action) => {
     // The answer is added  to an existing poll
     case RECEIVE_ANSWER: {
 
-        const { pollId, answer }: { pollId: string; answer: Answer } = action;
+        const { pollId, answer }: { answer: Answer, pollId: string; } = action;
 
         // if the poll doesn't exist
         if (!(pollId in state.polls)) {
diff --git a/react/features/polls/types.ts b/react/features/polls/types.ts
index 55d0f63c4..45038ac3a 100644
--- a/react/features/polls/types.ts
+++ b/react/features/polls/types.ts
@@ -34,7 +34,6 @@ export type Poll = {
      */
     changingVote: boolean,
 
-
     /**
      * The last sent votes for this poll, or null if voting was skipped
      * Note: This is reset when voting/skipping, not when clicking "Change vote".
diff --git a/react/features/power-monitor/reducer.js b/react/features/power-monitor/reducer.ts
similarity index 71%
rename from react/features/power-monitor/reducer.js
rename to react/features/power-monitor/reducer.ts
index 4bdc743b2..abfab6671 100644
--- a/react/features/power-monitor/reducer.js
+++ b/react/features/power-monitor/reducer.ts
@@ -1,17 +1,22 @@
-// @flow
-
+// @ts-ignore
 import { Transport } from '../../../modules/transport';
-import { ReducerRegistry, set } from '../base/redux';
+import ReducerRegistry from '../base/redux/ReducerRegistry';
+import { set } from '../base/redux/functions';
 
 import {
     SET_TRANSPORT,
     SUSPEND_DETECTED
 } from './actionTypes';
 
+export interface IPowerMonitorState {
+    suspendDetected?: boolean;
+    transport?: Transport;
+}
+
 /**
  * Reduces the redux actions of the feature power monitor.
  */
-ReducerRegistry.register('features/power-monitor', (state = { }, action) => {
+ReducerRegistry.register('features/power-monitor', (state: IPowerMonitorState = { }, action) => {
     switch (action.type) {
     case SET_TRANSPORT:
         return _setTransport(state, action.transport);
@@ -33,7 +38,7 @@ ReducerRegistry.register('features/power-monitor', (state = { }, action) => {
  * @returns {Object} The new state of the feature power monitor after the reduction of
  * the specified action.
  */
-function _setTransport(state, transport: ?Transport) {
+function _setTransport(state: IPowerMonitorState, transport?: Transport) {
     return set(state, 'transport', transport);
 }
 
@@ -45,7 +50,7 @@ function _setTransport(state, transport: ?Transport) {
  * @returns {Object} The new state of the feature overlay after the reduction of
  * the specified action.
  */
-function _suspendDetected(state) {
+function _suspendDetected(state: IPowerMonitorState) {
     return set(state, 'suspendDetected', true);
 }
 
diff --git a/react/features/prejoin/reducer.js b/react/features/prejoin/reducer.ts
similarity index 81%
rename from react/features/prejoin/reducer.js
rename to react/features/prejoin/reducer.ts
index 3cf37a388..940a7aeaf 100644
--- a/react/features/prejoin/reducer.js
+++ b/react/features/prejoin/reducer.ts
@@ -1,4 +1,5 @@
-import { PersistenceRegistry, ReducerRegistry } from '../base/redux';
+import PersistenceRegistry from '../base/redux/PersistenceRegistry';
+import ReducerRegistry from '../base/redux/ReducerRegistry';
 
 import {
     PREJOIN_JOINING_IN_PROGRESS,
@@ -33,16 +34,31 @@ const DEFAULT_STATE = {
     showJoinByPhoneDialog: false
 };
 
-/**
- * The name of the redux store/state property which is the root of the redux
- * state of the feature {@code prejoin}.
- */
-const STORE_NAME = 'features/prejoin';
+export interface IPrejoinState {
+    country: string;
+    deviceStatusText: string;
+    deviceStatusType: string;
+    dialOutCountry: {
+        code: string;
+        dialCode: string;
+        name: string;
+    };
+    dialOutNumber: string;
+    dialOutStatus: string;
+    isDisplayNameRequired: boolean;
+    joiningInProgress?: boolean;
+    name: string;
+    precallTestResults?: Object;
+    rawError: string;
+    showJoinByPhoneDialog: boolean;
+    showPrejoin: boolean;
+    skipPrejoinOnReload: boolean;
+}
 
 /**
  * Sets up the persistence of the feature {@code prejoin}.
  */
-PersistenceRegistry.register(STORE_NAME, {
+PersistenceRegistry.register('features/prejoin', {
     skipPrejoinOnReload: true
 }, DEFAULT_STATE);
 
@@ -50,7 +66,7 @@ PersistenceRegistry.register(STORE_NAME, {
  * Listen for actions that mutate the prejoin state.
  */
 ReducerRegistry.register(
-    'features/prejoin', (state = DEFAULT_STATE, action) => {
+    'features/prejoin', (state: IPrejoinState = DEFAULT_STATE, action) => {
         switch (action.type) {
         case PREJOIN_JOINING_IN_PROGRESS:
             return {
@@ -142,7 +158,11 @@ ReducerRegistry.register(
  * @param {Object} errors - The errors got while creating local tracks.
  * @returns {Object}
  */
-function getStatusFromErrors(errors) {
+function getStatusFromErrors(errors: {
+    audioAndVideoError?: {message: string},
+    audioOnlyError?: { message: string },
+    videoOnlyError?: Object }
+) {
     const { audioOnlyError, videoOnlyError, audioAndVideoError } = errors;
 
     if (audioAndVideoError) {
diff --git a/react/features/reactions/reducer.ts b/react/features/reactions/reducer.ts
index b25fda90b..ce4c8f5f3 100644
--- a/react/features/reactions/reducer.ts
+++ b/react/features/reactions/reducer.ts
@@ -9,7 +9,7 @@ import {
 } from './actionTypes';
 import { ReactionEmojiProps } from './constants';
 
-interface IReactionsState {
+export interface IReactionsState {
 
     /**
      * An array that contains the reactions buffer to be sent.