fix sockjs#403,add timeoutMs option

README.md

@@ -152,6 +152,10 @@ Where `options` is a hash which can contain:
     If you don't specify this option, the default is to use the default random
     string generator to generate 8-character long session ids.
 
+*  **timeoutMs (number)**
+
+    Timeout millseconds for transport connection, more information see [this issue](https://github.com/sockjs/sockjs-client/issues/403)
+
 Although the 'SockJS' object tries to emulate the 'WebSocket'
 behaviour, it's impossible to support all of its features. An
 important SockJS limitation is the fact that you're not allowed to

lib/main.js

@@ -49,7 +49,7 @@ function SockJS(url, protocols, options) {
   }
   this._transportsWhitelist = options.transports;
   this._transportOptions = options.transportOptions || {};
-
+  this._timeoutMs = options.timeoutMs;
   var sessionId = options.sessionId || 8;
   if (typeof sessionId === 'function') {
     this._generateSessionId = sessionId;
@@ -209,7 +209,7 @@ SockJS.prototype._connect = function() {
     }
 
     // calculate timeout based on RTO and round trips. Default to 5s
-    var timeoutMs = (this._rto * Transport.roundTrips) || 5000;
+    var timeoutMs = this._timeoutMs || (this._rto * Transport.roundTrips) || 5000;
     this._transportTimeoutId = setTimeout(this._transportTimeout.bind(this), timeoutMs);
     debug('using timeout', timeoutMs);