[feat] Detect React-Native environment and use all websocket features (#591)

React-Native provides a Websocket object that is more functionally aligned with the Node.js websocket than the browser websocket.

It has the same constructor signature as the Node.js websocket and can support extraHeaders and protocols.

This PR will detect when the engine.io-client is running in React-Native, call the proper Websocket constructor, and enable support for extraHeaders.

Author: cthayer

.gitignore

@@ -4,3 +4,4 @@ build
 components
 /coverage
 npm-debug.log
+.idea

lib/socket.js

@@ -94,9 +94,12 @@ function Socket (uri, opts) {
   this.rejectUnauthorized = opts.rejectUnauthorized === undefined ? true : opts.rejectUnauthorized;
   this.forceNode = !!opts.forceNode;
 
-  // other options for Node.js client
+  // detect ReactNative environment
+  this.isReactNative = (typeof navigator !== 'undefined' && typeof navigator.product === 'string' && navigator.product.toLowerCase() === 'reactnative');
+
+  // other options for Node.js or ReactNative client
   var freeGlobal = typeof global === 'object' && global;
-  if (freeGlobal.global === freeGlobal) {
+  if (freeGlobal.global === freeGlobal || this.isReactNative) {
     if (opts.extraHeaders && Object.keys(opts.extraHeaders).length > 0) {
       this.extraHeaders = opts.extraHeaders;
     }
@@ -196,7 +199,8 @@ Socket.prototype.createTransport = function (name) {
     forceNode: options.forceNode || this.forceNode,
     localAddress: options.localAddress || this.localAddress,
     requestTimeout: options.requestTimeout || this.requestTimeout,
-    protocols: options.protocols || void (0)
+    protocols: options.protocols || void (0),
+    isReactNative: this.isReactNative
   });
 
   return transport;

lib/transport.js

@@ -41,6 +41,9 @@ function Transport (opts) {
   this.rejectUnauthorized = opts.rejectUnauthorized;
   this.forceNode = opts.forceNode;
 
+  // results of ReactNative environment detection
+  this.isReactNative = opts.isReactNative;
+
   // other options for Node.js client
   this.extraHeaders = opts.extraHeaders;
   this.localAddress = opts.localAddress;

lib/transports/websocket.js

@@ -109,7 +109,7 @@ WS.prototype.doOpen = function () {
   }
 
   try {
-    this.ws = this.usingBrowserWebSocket ? (protocols ? new WebSocket(uri, protocols) : new WebSocket(uri)) : new WebSocket(uri, protocols, opts);
+    this.ws = this.usingBrowserWebSocket && !this.isReactNative ? (protocols ? new WebSocket(uri, protocols) : new WebSocket(uri)) : new WebSocket(uri, protocols, opts);
   } catch (err) {
     return this.emit('error', err);
   }