feat: allow to pass an array to io.to(...)

In some cases it is necessary to pass an array of rooms instead of a single room.

New syntax:

```
io.to(["room1", "room2"]).except(["room3"]).emit(...);

socket.to(["room1", "room2"]).except(["room3"]).emit(...);
```

Related: #3048

lib/broadcast-operator.ts

@@ -18,10 +18,16 @@ export class BroadcastOperator {
    * @return a new BroadcastOperator instance
    * @public
    */
-  public to(room: Room): BroadcastOperator {
+  public to(room: Room | Room[]): BroadcastOperator {
+    const rooms = new Set(this.rooms);
+    if (Array.isArray(room)) {
+      room.forEach((r) => rooms.add(r));
+    } else {
+      rooms.add(room);
+    }
     return new BroadcastOperator(
       this.adapter,
-      new Set([...this.rooms, room]),
+      rooms,
       this.exceptRooms,
       this.flags
     );
@@ -34,7 +40,7 @@ export class BroadcastOperator {
    * @return a new BroadcastOperator instance
    * @public
    */
-  public in(room: Room): BroadcastOperator {
+  public in(room: Room | Room[]): BroadcastOperator {
     return this.to(room);
   }
 
@@ -45,11 +51,17 @@ export class BroadcastOperator {
    * @return a new BroadcastOperator instance
    * @public
    */
-  public except(room: Room): BroadcastOperator {
+  public except(room: Room | Room[]): BroadcastOperator {
+    const exceptRooms = new Set(this.exceptRooms);
+    if (Array.isArray(room)) {
+      room.forEach((r) => exceptRooms.add(r));
+    } else {
+      exceptRooms.add(room);
+    }
     return new BroadcastOperator(
       this.adapter,
       this.rooms,
-      new Set([...this.exceptRooms, room]),
+      exceptRooms,
       this.flags
     );
   }

lib/index.ts

@@ -629,7 +629,7 @@ export class Server extends EventEmitter {
    * @return self
    * @public
    */
-  public to(room: Room): BroadcastOperator {
+  public to(room: Room | Room[]): BroadcastOperator {
     return this.sockets.to(room);
   }
 
@@ -640,7 +640,7 @@ export class Server extends EventEmitter {
    * @return self
    * @public
    */
-  public in(room: Room): BroadcastOperator {
+  public in(room: Room | Room[]): BroadcastOperator {
     return this.sockets.in(room);
   }
 
@@ -651,7 +651,7 @@ export class Server extends EventEmitter {
    * @return self
    * @public
    */
-  public except(name: Room): Server {
+  public except(name: Room | Room[]): Server {
     this.sockets.except(name);
     return this;
   }

lib/namespace.ts

@@ -100,7 +100,7 @@ export class Namespace extends EventEmitter {
    * @return self
    * @public
    */
-  public to(room: Room): BroadcastOperator {
+  public to(room: Room | Room[]): BroadcastOperator {
     return new BroadcastOperator(this.adapter).to(room);
   }
 
@@ -111,7 +111,7 @@ export class Namespace extends EventEmitter {
    * @return self
    * @public
    */
-  public in(room: Room): BroadcastOperator {
+  public in(room: Room | Room[]): BroadcastOperator {
     return new BroadcastOperator(this.adapter).in(room);
   }
 
@@ -122,7 +122,7 @@ export class Namespace extends EventEmitter {
    * @return self
    * @public
    */
-  public except(room: Room): BroadcastOperator {
+  public except(room: Room | Room[]): BroadcastOperator {
     return new BroadcastOperator(this.adapter).except(room);
   }
 

lib/socket.ts

@@ -175,7 +175,7 @@ export class Socket extends EventEmitter {
    * @return self
    * @public
    */
-  public to(room: Room): BroadcastOperator {
+  public to(room: Room | Room[]): BroadcastOperator {
     return this.newBroadcastOperator().to(room);
   }
 
@@ -186,7 +186,7 @@ export class Socket extends EventEmitter {
    * @return self
    * @public
    */
-  public in(room: Room): BroadcastOperator {
+  public in(room: Room | Room[]): BroadcastOperator {
     return this.newBroadcastOperator().in(room);
   }
 
@@ -197,7 +197,7 @@ export class Socket extends EventEmitter {
    * @return self
    * @public
    */
-  public except(room: Room): BroadcastOperator {
+  public except(room: Room | Room[]): BroadcastOperator {
     return this.newBroadcastOperator().except(room);
   }
 

test/socket.io.ts

@@ -392,7 +392,7 @@ describe("socket.io", () => {
 
     it("should return an immutable broadcast operator", () => {
       const sio = new Server();
-      const operator = sio.local.to("room1").to("room2").except("room3");
+      const operator = sio.local.to(["room1", "room2"]).except("room3");
       operator.compress(true).emit("hello");
       operator.volatile.emit("hello");
       operator.to("room4").emit("hello");
@@ -2362,8 +2362,7 @@ describe("socket.io", () => {
         sio.on("connection", (socket: Socket) => {
           const operator = socket.local
             .compress(false)
-            .to("room1")
-            .to("room2")
+            .to(["room1", "room2"])
             .except("room3");
           operator.compress(true).emit("hello");
           operator.volatile.emit("hello");