fix: silently close the transport in the beforeunload hook

Related: - socketio/socket.io#3639 - socketio/socket.io#3069

Author: darrachequesne

lib/socket.js

@@ -90,6 +90,20 @@ class Socket extends Emitter{
 // set on heartbeat
 this.pingTimeoutTimer=null;
 
+if(typeofaddEventListener==="function"){
+addEventListener(
+"beforeunload",
+()=>{
+if(this.transport){
+// silently close the transport
+this.transport.removeAllListeners();
+this.transport.close();
+}
+},
+false
+);
+}
+
 this.open();
 }
 

lib/transports/polling-jsonp.js

@@ -10,12 +10,6 @@ const rEscapedNewline = /\\n/g;
 
 letcallbacks;
 
-/**
- * Noop.
- */
-
-functionempty(){}
-
 classJSONPPollingextendsPolling{
 /**
  * JSONP Polling constructor.
@@ -46,17 +40,6 @@ class JSONPPolling extends Polling{
 
 // append to query string
 this.query.j=this.index;
-
-// prevent spurious errors from being emitted when the window is unloaded
-if(typeofaddEventListener==="function"){
-addEventListener(
-"beforeunload",
-function(){
-if(self.script)self.script.onerror=empty;
-},
-false
-);
-}
 }
 
 /**
@@ -73,6 +56,8 @@ class JSONPPolling extends Polling{
  */
 doClose(){
 if(this.script){
+// prevent spurious errors from being emitted when the window is unloaded
+this.script.onerror=()=>{};
 this.script.parentNode.removeChild(this.script);
 this.script=null;
 }

lib/transports/websocket.js

@@ -201,6 +201,7 @@ class WS extends Transport{
 doClose(){
 if(typeofthis.ws!=="undefined"){
 this.ws.close();
+this.ws=null;
 }
 }