[fix] Fix extentions property type

Make `extensions` a getter that returns the negotiated extensions
names.

Fixes #1244

Author: lpinca

Diff for: lib/websocket-server.js

@@ -261,7 +261,7 @@ class WebSocketServer extends EventEmitter {
         [PerMessageDeflate.extensionName]: [params]
       });
       headers.push(`Sec-WebSocket-Extensions: ${value}`);
-      ws.extensions = extensions;
+      ws._extensions = extensions;
     }
 
     //

Diff for: lib/websocket.js

@@ -41,7 +41,6 @@ class WebSocket extends EventEmitter {
     super();
 
     this.readyState = WebSocket.CONNECTING;
-    this.extensions = {};
     this.protocol = '';
 
     this._binaryType = constants.BINARY_TYPES[0];
@@ -52,6 +51,7 @@ class WebSocket extends EventEmitter {
     this._closeTimer = null;
     this._finalized = false;
     this._closeCode = 1006;
+    this._extensions = {};
     this._isServer = true;
     this._receiver = null;
     this._sender = null;
@@ -77,18 +77,6 @@ class WebSocket extends EventEmitter {
   get CLOSED () { return WebSocket.CLOSED; }
   get OPEN () { return WebSocket.OPEN; }
 
-  /**
-   * @type {Number}
-   */
-  get bufferedAmount () {
-    var amount = 0;
-
-    if (this._socket) {
-      amount = this._socket.bufferSize + this._sender._bufferedBytes;
-    }
-    return amount;
-  }
-
   /**
    * This deviates from the WHATWG interface since ws doesn't support the required
    * default "blob" type (instead we define a custom "nodebuffer" type).
@@ -110,6 +98,25 @@ class WebSocket extends EventEmitter {
     if (this._receiver) this._receiver._binaryType = type;
   }
 
+  /**
+   * @type {Number}
+   */
+  get bufferedAmount () {
+    var amount = 0;
+
+    if (this._socket) {
+      amount = this._socket.bufferSize + this._sender._bufferedBytes;
+    }
+    return amount;
+  }
+
+  /**
+   * @type {String}
+   */
+  get extensions () {
+    return Object.keys(this._extensions).join();
+  }
+
   /**
    * Set up the socket and the internal resources.
    *
@@ -122,8 +129,8 @@ class WebSocket extends EventEmitter {
     socket.setTimeout(0);
     socket.setNoDelay();
 
-    this._receiver = new Receiver(this.extensions, maxPayload, this.binaryType);
-    this._sender = new Sender(socket, this.extensions);
+    this._receiver = new Receiver(this._extensions, maxPayload, this.binaryType);
+    this._sender = new Sender(socket, this._extensions);
     this._ultron = new Ultron(socket);
     this._socket = socket;
 
@@ -211,12 +218,10 @@ class WebSocket extends EventEmitter {
 
     this.emit('close', this._closeCode, this._closeMessage);
 
-    if (this.extensions[PerMessageDeflate.extensionName]) {
-      this.extensions[PerMessageDeflate.extensionName].cleanup();
+    if (this._extensions[PerMessageDeflate.extensionName]) {
+      this._extensions[PerMessageDeflate.extensionName].cleanup();
     }
 
-    this.extensions = null;
-
     this.removeAllListeners();
   }
 
@@ -413,7 +418,7 @@ class WebSocket extends EventEmitter {
       fin: true
     }, options);
 
-    if (!this.extensions[PerMessageDeflate.extensionName]) {
+    if (!this._extensions[PerMessageDeflate.extensionName]) {
       opts.compress = false;
     }
 
@@ -722,7 +727,7 @@ function initAsClient (address, protocols, options) {
           perMessageDeflate.accept(
             extensions[PerMessageDeflate.extensionName]
           );
-          this.extensions[PerMessageDeflate.extensionName] = perMessageDeflate;
+          this._extensions[PerMessageDeflate.extensionName] = perMessageDeflate;
         }
       } catch (err) {
         socket.destroy();