feat: allow to exclude specific rooms when broadcasting (#3789)

New syntax:

```
io.except("room1").emit(...);
io.to("room1").except("room2").emit(...);

socket.broadcast.except("room1").emit(...);
socket.to("room1").except("room2").emit(...);
```

Related:

- #3629
- #3657

lib/index.ts

@@ -645,6 +645,18 @@ export class Server extends EventEmitter {
     return this;
   }
 
+  /**
+   * Excludes a room when emitting.
+   *
+   * @param name
+   * @return self
+   * @public
+   */
+  public except(name: Room): Server {
+    this.sockets.except(name);
+    return this;
+  }
+
   /**
    * Sends a `message` event to all clients.
    *

lib/namespace.ts

@@ -29,6 +29,9 @@ export class Namespace extends EventEmitter {
   /** @private */
   _rooms: Set<Room> = new Set();
 
+  /** @private */
+  _except: Set<Room> = new Set();
+
   /** @private */
   _flags: any = {};
 
@@ -123,6 +126,18 @@ export class Namespace extends EventEmitter {
     return this;
   }
 
+  /**
+   * Excludes a room when emitting.
+   *
+   * @param name
+   * @return self
+   * @public
+   */
+  public except(name: Room): Namespace {
+    this._except.add(name);
+    return this;
+  }
+
   /**
    * Adds a new client.
    *
@@ -203,14 +218,17 @@ export class Namespace extends EventEmitter {
 
     const rooms = new Set(this._rooms);
     const flags = Object.assign({}, this._flags);
+    const except = new Set(this._except);
 
     // reset flags
     this._rooms.clear();
     this._flags = {};
+    this._except.clear();
 
     this.adapter.broadcast(packet, {
       rooms: rooms,
       flags: flags,
+      except: except,
     });
 
     return true;

lib/socket.ts

@@ -92,6 +92,7 @@ export class Socket extends EventEmitter {
   > = [];
   private flags: BroadcastFlags = {};
   private _rooms: Set<Room> = new Set();
+  private _except: Set<Room> = new Set();
   private _anyListeners?: Array<(...args: any[]) => void>;
 
   /**
@@ -166,14 +167,16 @@ export class Socket extends EventEmitter {
 
     const rooms = new Set(this._rooms);
     const flags = Object.assign({}, this.flags);
+    const except = new Set(this._except);
 
     // reset flags
     this._rooms.clear();
     this.flags = {};
+    this._except.clear();
 
     if (rooms.size || flags.broadcast) {
       this.adapter.broadcast(packet, {
-        except: new Set([this.id]),
+        except: new Set([this.id, ...except]),
         rooms: rooms,
         flags: flags,
       });
@@ -208,6 +211,18 @@ export class Socket extends EventEmitter {
     return this;
   }
 
+  /**
+   * Excludes a room when broadcasting.
+   *
+   * @param name
+   * @return self
+   * @public
+   */
+  public except(name: Room): Socket {
+    this._except.add(name);
+    return this;
+  }
+
   /**
    * Sends a `message` event.
    *

package.json

@@ -50,7 +50,7 @@
     "base64id": "~2.0.0",
     "debug": "~4.3.1",
     "engine.io": "~4.1.0",
-    "socket.io-adapter": "~2.1.0",
+    "socket.io-adapter": "~2.2.0",
     "socket.io-parser": "~4.0.3"
   },
   "devDependencies": {

test/socket.io.ts

@@ -823,6 +823,57 @@ describe("socket.io", () => {
       });
     });
 
+    it("should exclude a specific socket when emitting", (done) => {
+      const srv = createServer();
+      const sio = new Server(srv);
+
+      const nsp = sio.of("/nsp");
+
+      srv.listen(() => {
+        const socket1 = client(srv, "/nsp");
+        const socket2 = client(srv, "/nsp");
+
+        socket2.on("a", () => {
+          done(new Error("not"));
+        });
+        socket1.on("a", () => {
+          done();
+        });
+
+        socket2.on("connect", () => {
+          nsp.except(socket2.id).emit("a");
+        });
+      });
+    });
+
+    it("should exclude a specific room when emitting", (done) => {
+      const srv = createServer();
+      const sio = new Server(srv);
+
+      const nsp = sio.of("/nsp");
+
+      srv.listen(() => {
+        const socket1 = client(srv, "/nsp");
+        const socket2 = client(srv, "/nsp");
+
+        socket1.on("a", () => {
+          done();
+        });
+        socket2.on("a", () => {
+          done(new Error("not"));
+        });
+
+        nsp.on("connection", (socket) => {
+          socket.on("broadcast", () => {
+            socket.join("room1");
+            nsp.except("room1").emit("a");
+          });
+        });
+
+        socket2.emit("broadcast");
+      });
+    });
+
     describe("dynamic namespaces", () => {
       it("should allow connections to dynamic namespaces with a regex", (done) => {
         const srv = createServer();
@@ -2222,6 +2273,72 @@ describe("socket.io", () => {
         });
       });
     });
+
+    it("should exclude specific sockets when broadcasting", (done) => {
+      const srv = createServer();
+      const sio = new Server(srv);
+
+      srv.listen(() => {
+        const socket1 = client(srv, { multiplex: false });
+        const socket2 = client(srv, { multiplex: false });
+        const socket3 = client(srv, { multiplex: false });
+
+        socket2.on("a", () => {
+          done(new Error("not"));
+        });
+        socket3.on("a", () => {
+          done(new Error("not"));
+        });
+        socket1.on("a", () => {
+          done();
+        });
+
+        sio.on("connection", (socket) => {
+          socket.on("exclude", (id) => {
+            socket.broadcast.except(id).emit("a");
+          });
+        });
+
+        socket2.on("connect", () => {
+          socket3.emit("exclude", socket2.id);
+        });
+      });
+    });
+
+    it("should exclude a specific room when broadcasting", (done) => {
+      const srv = createServer();
+      const sio = new Server(srv);
+
+      srv.listen(() => {
+        const socket1 = client(srv, { multiplex: false });
+        const socket2 = client(srv, { multiplex: false });
+        const socket3 = client(srv, { multiplex: false });
+
+        socket2.on("a", () => {
+          done(new Error("not"));
+        });
+        socket3.on("a", () => {
+          done(new Error("not"));
+        });
+        socket1.on("a", () => {
+          done();
+        });
+
+        sio.on("connection", (socket) => {
+          socket.on("join", (room, cb) => {
+            socket.join(room);
+            cb();
+          });
+          socket.on("broadcast", () => {
+            socket.broadcast.except("room1").emit("a");
+          });
+        });
+
+        socket2.emit("join", "room1", () => {
+          socket3.emit("broadcast");
+        });
+      });
+    });
   });
 
   describe("middleware", () => {