Add "use strict" directive to all .js files

src/qml/EventHandlers/app.js

@@ -1,6 +1,8 @@
 // Copyright 2019 miruka
 // This file is part of harmonyqml, licensed under LGPLv3.
 
+"use strict"
+
 function onExitRequested(exitCode) {
     Qt.exit(exitCode)
 }

src/qml/EventHandlers/includes.js

@@ -1,6 +1,8 @@
 // Copyright 2019 miruka
 // This file is part of harmonyqml, licensed under LGPLv3.
 
+"use strict"
+
 // FIXME: Obsolete method, but need Qt 5.12+ for standard JS modules import
 Qt.include("app.js")
 Qt.include("users.js")

src/qml/EventHandlers/rooms.js

@@ -1,6 +1,8 @@
 // Copyright 2019 miruka
 // This file is part of harmonyqml, licensed under LGPLv3.
 
+"use strict"
+
 Qt.include("../utils.js")
 
 function typingTextFor(members, ourUserId) {

src/qml/EventHandlers/users.js

@@ -1,6 +1,8 @@
 // Copyright 2019 miruka
 // This file is part of harmonyqml, licensed under LGPLv3.
 
+"use strict"
+
 function onAccountUpdated(userId) {
     accounts.append({userId})
 }

src/qml/utils.js

@@ -1,6 +1,8 @@
 // Copyright 2019 miruka
 // This file is part of harmonyqml, licensed under LGPLv3.
 
+"use strict"
+
 
 function hsl(hue, saturation, lightness) {
     return hsla(hue, saturation, lightness)