[No QA][TS migration] Migrate 'Visibility' lib to TypeScript

src/libs/Visibility/index.desktop.js → src/libs/Visibility/index.desktop.ts

@@ -1,31 +1,19 @@
 import ELECTRON_EVENTS from '../../../desktop/ELECTRON_EVENTS';
+import {HasFocus, IsVisible, OnVisibilityChange} from './types';
 
 /**
  * Detects whether the app is visible or not. Electron supports document.visibilityState,
  * but switching to another app while Electron is partially occluded will not trigger a state of hidden
  * so we ask the main process synchronously whether the BrowserWindow.isFocused()
- *
- * @returns {Boolean}
  */
-function isVisible() {
-    return window.electron.sendSync(ELECTRON_EVENTS.REQUEST_VISIBILITY);
-}
+const isVisible: IsVisible = () => !!window.electron.sendSync(ELECTRON_EVENTS.REQUEST_VISIBILITY);
 
-/**
- * @returns {Boolean}
- */
-function hasFocus() {
-    return true;
-}
+const hasFocus: HasFocus = () => true;
 
 /**
  * Adds event listener for changes in visibility state
- *
- * @param {Function} callback
- *
- * @return {Function} removes the listener
  */
-function onVisibilityChange(callback) {
+const onVisibilityChange: OnVisibilityChange = (callback) => {
     // Deliberately strip callback argument to be consistent across implementations
     window.electron.on(ELECTRON_EVENTS.FOCUS, () => callback());
     window.electron.on(ELECTRON_EVENTS.BLUR, () => callback());
@@ -34,7 +22,7 @@ function onVisibilityChange(callback) {
         window.electron.removeAllListeners(ELECTRON_EVENTS.FOCUS);
         window.electron.removeAllListeners(ELECTRON_EVENTS.BLUR);
     };
-}
+};
 
 export default {
     isVisible,

src/libs/Visibility/index.native.js → src/libs/Visibility/index.native.ts

@@ -2,32 +2,21 @@
 // they do not use the Notification lib.
 
 import {AppState} from 'react-native';
+import {HasFocus, IsVisible, OnVisibilityChange} from './types';
 
-/**
- * @return {Boolean}
- */
-const isVisible = () => AppState.currentState === 'active';
+const isVisible: IsVisible = () => AppState.currentState === 'active';
 
-/**
- * @returns {Boolean}
- */
-function hasFocus() {
-    return true;
-}
+const hasFocus: HasFocus = () => true;
 
 /**
  * Adds event listener for changes in visibility state
- *
- * @param {Function} callback
- *
- * @return {Function} removes the listener
  */
-function onVisibilityChange(callback) {
+const onVisibilityChange: OnVisibilityChange = (callback) => {
     // Deliberately strip callback argument to be consistent across implementations
     const subscription = AppState.addEventListener('change', () => callback());
 
     return () => subscription.remove();
-}
+};
 
 export default {
     isVisible,

src/libs/Visibility/index.js → src/libs/Visibility/index.ts

@@ -1,36 +1,25 @@
 import {AppState} from 'react-native';
+import {HasFocus, IsVisible, OnVisibilityChange} from './types';
 
 /**
  * Detects whether the app is visible or not.
- *
- * @returns {Boolean}
  */
-function isVisible() {
-    return document.visibilityState === 'visible';
-}
+const isVisible: IsVisible = () => document.visibilityState === 'visible';
 
 /**
  * Whether the app is focused.
- *
- * @returns {Boolean}
  */
-function hasFocus() {
-    return document.hasFocus();
-}
+const hasFocus: HasFocus = () => document.hasFocus();
 
 /**
  * Adds event listener for changes in visibility state
- *
- * @param {Function} callback
- *
- * @return {Function} removes the listener
  */
-function onVisibilityChange(callback) {
+const onVisibilityChange: OnVisibilityChange = (callback) => {
     // Deliberately strip callback argument to be consistent across implementations
     const subscription = AppState.addEventListener('change', () => callback());
 
     return () => subscription.remove();
-}
+};
 
 export default {
     isVisible,

src/libs/Visibility/types.ts

@@ -0,0 +1,5 @@
+type IsVisible = () => boolean;
+type HasFocus = () => boolean;
+type OnVisibilityChange = (callback: () => void) => () => void;
+
+export type {IsVisible, HasFocus, OnVisibilityChange};

src/types/modules/electron.d.ts

@@ -0,0 +1,9 @@
+declare global {
+    // eslint-disable-next-line @typescript-eslint/consistent-type-definitions
+    interface Window {
+        electron: Electron.IpcRenderer;
+    }
+}
+
+// We used the export {} line to mark this file as an external module
+export {};