Add WebSocket connected() function

src/client/WebSocketClient.test.ts

@@ -77,6 +77,44 @@ describe('WebSocketClient', () => {
     });
   });
 
+  describe('connected', () => {
+    it('returns false when called before the connection is created', done => {
+      const ws = createWebSocketClient();
+      expect(ws.connected).toBe(false);
+      done();
+    });
+    it('returns true when called after the connection is created', done => {
+      const ws = createWebSocketClient();
+
+      ws.on(WebSocketEvent.ON_CLOSE, () => {
+        done();
+      });
+
+      ws.on(WebSocketEvent.ON_OPEN, () => {
+        expect(ws.connected).toBe(true);
+
+        ws.disconnect();
+      });
+
+      ws.connect();
+    });
+
+    it('returns false when called after the connection is closed', done => {
+      const ws = createWebSocketClient();
+
+      ws.on(WebSocketEvent.ON_CLOSE, () => {
+        expect(ws.connected).toBe(false);
+        done();
+      });
+
+      ws.on(WebSocketEvent.ON_OPEN, () => {
+        ws.disconnect();
+      });
+
+      ws.connect();
+    });
+  });
+
   describe('constructor', () => {
     it('it signals an event when the WebSocket connection is established', done => {
       const ws = createWebSocketClient();

src/client/WebSocketClient.ts

@@ -331,6 +331,15 @@ export class WebSocketClient extends EventEmitter {
     }
   }
 
+  /**
+   * A simple function to determine if the websocket appears to be open.
+   *
+   * @returns True if the websocket has been opened and has not closed.
+   */
+  get connected(): boolean {
+    return undefined !== this.socket;
+  }
+
   async sendMessage(message: WebSocketRequest): Promise<void> {
     if (!this.socket) {
       throw new Error(`Failed to send message of type "${message.type}": You need to connect to the WebSocket first.`);