Code improvement

packages/rocketchat-lib/server/methods/addUsersToRoom.js

 Meteor.methods({
-	addUsersToRoom: function(data) {
-		var ref, room, user, userId, userInRoom, canAddUser;
-
+	addUsersToRoom(data = {}) {
 		// Validate user and room
 		if (!Meteor.userId()) {
 			throw new Meteor.Error('error-invalid-user', 'Invalid user', {
 				method: 'addUsersToRoom'
 			});
 		}
-		if (!Match.test(data != null ? data.rid : void 0, String)) {
+
+		if (!Match.test(data.rid, String)) {
 			throw new Meteor.Error('error-invalid-room', 'Invalid room', {
 				method: 'addUsersToRoom'
 			});
 		}
 
 		// Get user and room details
-		room = RocketChat.models.Rooms.findOneById(data.rid);
-		userId = Meteor.userId();
-		user = Meteor.user();
-		userInRoom = ((ref = room.usernames) != null ? ref.indexOf(user.username) : void 0) >= 0;
+		const room = RocketChat.models.Rooms.findOneById(data.rid);
+		const userId = Meteor.userId();
+		const user = Meteor.user();
+		const userInRoom = Array.isArray(room.usernames) && room.usernames.includes(user.username);
 
 		// Can't add to direct room ever
 		if (room.t === 'd') {
@@ -28,7 +27,7 @@ Meteor.methods({
 		}
 
 		// Can add to any room you're in, with permission, otherwise need specific room type permission
-		canAddUser = false;
+		let canAddUser = false;
 		if (userInRoom && RocketChat.authz.hasPermission(userId, 'add-user-to-joined-room', room._id)) {
 			canAddUser = true;
 		} else if (room.t === 'c' && RocketChat.authz.hasPermission(userId, 'add-user-to-any-c-room')) {
@@ -52,17 +51,17 @@ Meteor.methods({
 		}
 
 		// Validate each user, then add to room
-		data.users.forEach(function(username) {
-			let newUser = RocketChat.models.Users.findOneByUsername(username);
-			if (newUser == null) {
+		data.users.forEach((username) => {
+			const newUser = RocketChat.models.Users.findOneByUsername(username);
+			if (!newUser) {
 				throw new Meteor.Error('error-invalid-username', 'Invalid username', {
 					method: 'addUsersToRoom'
 				});
 			}
+
 			RocketChat.addUserToRoom(data.rid, newUser, user);
 		});
 
 		return true;
-
 	}
 });

server/startup/migrations/v084.js

 RocketChat.Migrations.add({
 	version: 84,
-	up: function() {
-		if (RocketChat && RocketChat.models && RocketChat.models.Permissions) {
+	up() {
+		if (RocketChat.models && RocketChat.models.Permissions) {
 
 			// Update permission name, copy values from old name
 			var oldPermission = RocketChat.models.Permissions.findOne('add-user-to-room');
@@ -9,11 +9,11 @@ RocketChat.Migrations.add({
 				RocketChat.models.Permissions.upsert({ _id: 'add-user-to-joined-room' }, { $set: { roles: oldPermission.roles } });
 				RocketChat.models.Permissions.remove({ _id: 'add-user-to-room' });
 			}
-
 		}
 	},
-	down: function() {
-		if (RocketChat && RocketChat.models && RocketChat.models.Permissions) {
+
+	down() {
+		if (RocketChat.models && RocketChat.models.Permissions) {
 
 			// Revert permission name, copy values from updated name
 			var newPermission = RocketChat.models.Permissions.findOne('add-user-to-joined-room');
@@ -21,7 +21,6 @@ RocketChat.Migrations.add({
 				RocketChat.models.Permissions.upsert({ _id: 'add-user-to-room' }, { $set: { roles: newPermission.roles } });
 				RocketChat.models.Permissions.remove({ _id: 'add-user-to-joined-room' });
 			}
-
 		}
 	}
 });